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    Keto Tuna Casserole | One of The Best Keto Casserole Recipes

    by Joe Duff 46 Comments

    Jump to Recipe

    This keto tuna casserole is made with mushrooms and spinach and is packed with two types of cheese - making it the ultimate cheesy tuna casserole! And it's not only flavorful & creamy, but it's nutritious too. Honestly, this might just be one of the best keto casserole recipes you can make.

    Keto tuna casserole in a white casserole dish. The side of a metal spoon head is touching the surface of the back corner of the casserole. The white dish is on a wooden cutting board on a white counter. A bowl of seasonings is behind the cutting board.

    THE BEST KETO TUNA CASSEROLE

    This low carb tuna casserole has everything that makes a great keto recipe.

    It filled with keto-friendly vegetables, creamy melted cheese, has a ton of flavor, and yields multiple servings. 

    And of course, it's a low carb tuna casserole! There's only 3 NET CARBS per serving.

    Also, this keto tuna casserole is loaded with nutrients and it is gluten free, making it a super healthy meal. 

    Tuna is not only a great source of protein but it's also an excellent way to get your daily dose of omega-3 fatty acids and vitamin B6. Top that off with the mushrooms and spinach, and you've got yourself one super healthy dish. 

    Plus, this low carb keto recipe is incredibly quick and easy to make, and you can have it ready and on the table in under 30 minutes. 

    Oh, and if you're looking for more low carb casseroles, check out this asparagus casserole and cheesy spinach casserole next!

    Keto tuna casserole in a white casserole dish. The front corner of the casserole has a piece gone, showing the mushrooms and tuna in the dish.

    INGREDIENTS FOR KETO TUNA CASSEROLE

    Now, typically, tuna casserole is made with bread crumbs and noodles, causing the dish to have upwards of 60 grams of carbs per serving. 

    For this low carb tuna casserole though, we will be using almond flour in place of bread crumbs to keep the carbs down but still give this casserole a crispy, crunchy surface, just like with these keto chicken nuggets. 

    Also, we'll be using mushrooms instead of noodles to make this recipe even more low carb and gluten free. 

    Having said all of that, here's the complete list of things you'll need to make this low carb keto casserole:

    • 2 tbsps butter 
    • ½ onion, chopped 
    • 2 cups sliced mushrooms
    • 1 cup chopped spinach
    • 2 five ounce cans of tuna packed in water, drained
    • 1 cup grated mozzarella cheese 
    • 1 cup cream cheese, cubed
    • 1 teaspoon Italian seasoning
    • Salt and pepper to taste
    • 2 cups shredded Cheddar Cheese 
    • 2 tbsp almond flour

    Combining the ingredients in this recipe makes this casserole irresistibly delicious and turns regular tuna casserole into super healthy comfort food.

    And it's easy to make, and even easier to clean up.

    So you know I'm a big fan of that.

    An overhead view of keto tuna casserole in a white casserole dish on top of a wooden cutting board with a handle. A small bowl of seasonings and three forks are on a grey tablecloth to the right of the casserole dish. A white plate with a scoop of tune casserole on it is in front the casserole dish. There is a spoon at the edge of the dish and everything is on a white counter.

    GRATE YOUR OWN CHEESE 

    We are going to be using mozzarella and cheddar cheese to give this tuna casserole its delicious cheesiness. 

    Although both of these cheeses come pre-shredded, I recommend shredding your own cheese with a cheese grater. 

    The pre-shredded cheeses that you can buy at the store typically have added starches in them. 

    The added starches prevent the cheese from clumping and sticking together. But, these starches contain unnecessary carbohydrates.

    So, to keep your keto tuna casserole - and other low carb recipes - as low carb as possible, avoid the pre-shredded kind. 

    Now, if you already have the pre-shredded cheese on hand or don't want to buy a block of cheese, don't worry. This dish is already super low in carbs, thanks to the rest of the ingredients, so feel free to use it.

    By the way, to make this even cheesier, you can sprinkle some parmesan cheese on top after it gets out of the oven.

    An overhead view of a white casserole dish filled with keto tuna casserole. A wood spoon with the metal head is in the corner of the casserole with tuna casserole on the head. A couple of forks are on a grey tablecloth to the left of the casserole dish.

    ARE MUSHROOMS KETO?

    As I mentioned earlier, we will be using mushrooms in place of noodles for this tuna casserole. 

    Now, mushrooms tend to get overlooked and not many people realize just how great they are for keto. 

    In fact, mushrooms might be the best low carb keto "vegetable" you can have.

    First off, mushrooms are super low in calories and carbs. Each cup has about 16 calories and a low carb count - about 1.5 grams.

    Secondly, mushrooms are packed with fiber and water, making them a "bulk" food. And this means that they can make you feel full without eating a lot of them.

    Plus, mushrooms are high in potassium, which is an essential mineral and electrolyte. And potassium is vital on the keto diet because your body flushes out a lot of water since you are not eating carbs to retain it. 

    So, the verdict is that mushrooms are keto friendly, and one of the best keto foods you can eat. 

    Keto tuna casserole in a white casserole dish. The head of a metal spoon is at the front of the casserole dish and is filled with mushrooms. The casserole dish is on a wooden board.

    Mushrooms to use for this casserole

    Ok, so we know mushrooms are perfect for this low carb tuna casserole, but what mushrooms should you use?

    There are various mushrooms to choose from, and you really can use any ones you want.

    With that said, I suggest using sliced white or brown button mushrooms, cremini mushrooms, or mini-portobellos.

    I think these mushrooms pair best with the overall flavor in this tuna casserole. 

    HOW TO MAKE KETO TUNA CASSEROLE

    Ok, so now let's get into the nitty-gritty on how to make this low carb keto casserole.

    One of the reasons I love this gluten free casserole is that it only requires a few steps and it is so quick and easy to make.

    All you have to do is sauté the vegetables, incorporate the rest of the ingredients, then bake everything in the oven, and you'll have yourself a delicious casserole ready to go. 

    Now, if you're ready to make this recipe, let's get to it!

    A full keto tuna casserole in a white casserole dish. The casserole dish is on a wooden cutting board on top of a white counter. There is a wood spoon with the metal head resting on the back left corner of the casserole. A small bowl of seasonings is on the counter behind the spoon and a few forks are in front of it.

    STEP 1: PREP

    First off, you'll want to preheat your oven to 350°F (176°C) and coat a 9x13 baking dish with cooking spray.

    Next, you'll want to prepare the vegetables. Chop the spinach and onions, then slice the mushrooms. 

    STEP 2: SAUTE THE VEGETABLES

    Now we're all set to start sauteing our vegetables.

    So, to begin the sauteing process, you'll want to melt the butter in a large pan over high-heat. 

    Next, add the onions and saute for 3 minutes. Then, once the onions have softened, add the mushrooms.

    Cook the mushrooms for about 5 minutes on high-heat to reduce the moisture in them. And make sure you stir the mushrooms often while cooking.

    Lastly, add the spinach, stir them until they're wilted, and turn the heat down to low.

    STEP 3: COMBINE ALL THE INGREDIENTS

    Now you're all set to add the cream cheese, grated mozzarella, Italian seasoning, salt, and pepper to the pan.

    Cook everything and stir until the cheese just starts to melt and combines with the other ingredients.

    After that, add the drained tuna and stir together until everything is combined. 

    STEP 4: ASSEMBLE AND BAKE

    So, at this point, you'll want to spoon the tuna mixture evenly into the baking dish. 

    Then, sprinkle the shredded cheddar on top, followed by the almond flour.

    Bake for a total time of 15-20 minutes, or until the surface is crisped and golden brown.

    Let it cool for a few minutes in the baking dish, sprinkle some parmesan cheese on top, and then this casserole is ready to serve!

    An overhead view of a white plate with keto tuna casserole on it with a metal spoon on the front edge of the plate. A casserole dish filled with the keto tuna casserole is directly behind the plate slightly off to the right. The plate is on a white counter and the casserole dish is on a wooden board on the counter

    STORING YOUR KETO TUNA CASSEROLE

    While low carb tuna casserole is best enjoyed fresh, this recipe makes about 10 servings, giving you a delicious leftover meal for the next few days. 

    You can store your leftovers in an airtight container in the refrigerator for up to 3 days. If your baking dish has a lid to it, simply pop it on and put the casserole dish in the fridge. 

    For reheating the refrigerated casserole, put it in the oven at 350° F (176°C) until warm, about 20-30 minutes, then sprinkle some grated parmesan on top and dig in!

    FREEZING YOUR CASSEROLE 

    You also have the option to freeze this casserole if you would like for it to last longer.

    It can be frozen for up to 6 months, as long as you store it in an airtight, freezer-safe container.

    To reheat the casserole that has been frozen, you have two options. 

    First, you can let it thaw in the fridge, then reheat in the oven at 350°F (176°C) for about 20-30 minutes until it reaches your desired temperature. 

    However, you can also reheat frozen tuna casserole directly in the oven, though this will take significantly longer, sometimes up to an hour.

    Just make sure that you let your frozen tuna casserole come to room temperature before popping it in the oven to avoid the dish's glass breaking due to extreme temperature change.

    Also, it can be reheated in the microwave, but you may lose some of the crunchiness on the surface layer you get when baking and reheating in the oven.

    An overhead view of a white casserole dish filled with keto tuna casserole. A wood spoon with the metal head is in the corner of the casserole with tuna casserole on the head. A couple of forks are on a grey tablecloth to the left of the casserole dish.

    NUTRITIONAL INFORMATION

    As I mentioned above, this gluten free and keto tuna casserole has just 3 NET CARBS per serving. Pretty good for a dish that traditionally has a super high carb count.

    So, this recipe makes a 10 serving casserole, but the full nutritional information for 1 serving is as follows:

    • 239 Calories
    • 19g Fat
    • 4g Carbs
    • 1g Fiber
    • 3g NET CARBS
    • 14.4g Protein

    Now, since this recipe makes so many servings, it is a great meal to make and have on hand for lunch or dinner the next couple of days. Meal prep anyone?!

    Or, if you want to make this dish for a family dinner, you'll easily be able to feed everyone.

    And trust me, they'll enjoy this low carb tuna casserole just as much as a non-keto tuna casserole. 

    Anyway, I hope you like this keto tuna casserole as much as I do, and if you try it out, let me know what you think in the comments below.

    Print

    Keto Tuna Casserole | One of The Best Keto Casserole Recipes

    Keto tuna casserole in a white casserole dish. The side of a metal spoon head is touching the surface of the back corner of the casserole. The white dish is on a wooden cutting board on a white counter. A bowl of seasonings is behind the cutting board.
    Print Recipe

    ★★★★★

    5 from 41 reviews

    This keto tuna casserole is made with mushrooms and spinach and is packed with two types of cheese - making it the ultimate cheesy tuna casserole recipe! It's not only flavorful & creamy, but it's nutritious too.  And, honestly, it might just be one of the best keto casserole recipes you can make.

    • Author: I'm Hungry
    • Prep Time: 15 minutes
    • Cook Time: 15 minutes
    • Total Time: 30 minutes
    • Yield: 10 servings 1x
    • Category: Dinner
    • Method: Stovetop/Oven
    • Cuisine: Keto Low carb

    Ingredients

    Scale

    2 tbsps (28g) butter 

    ½ onion (60g), chopped 

    2 cups (200g) sliced mushrooms

    1 cup (30g) chopped spinach

    2 five ounce cans of tuna packed in water, drained

    1 cup (112g) grated mozzarella cheese 

    1 cup (113g) cream cheese, cubed 

    1 teaspoon Italian seasoning

    Salt and pepper to taste

    2 cups (224g) shredded Cheddar Cheese 

    2 tbsp (28g) almond flour 

    Instructions

    1. Preheat the oven to 350°F (176°C) and coat a 9x13 casserole dish with cooking spray.
    2. Chop the spinach and onions, then slice the mushrooms. 
    3. To begin cooking, melt the butter in a large pan over high heat. Add the onions and saute for 3 minutes. 
    4. Once the onions have softened, add the mushrooms and cook for about 5 minutes on high heat, stirring often.
    5. Now, once the mushrooms have softened - and reduced in size - add in the spinach, stir until wilted, and then turn the heat down to low.
    6. Then, when the spinach has wilted, add the cream cheese, grated mozzarella, Italian seasoning, salt, and pepper to the pan.
    7. Cook everything until the cheese just starts to melt and combines with the other ingredients.
    8. Then, add the drained tuna and stir together until everything is combined. 
    9. Once everything combines, spoon the tuna mixture evenly into the casserole dish.
    10. Sprinkle the shredded cheddar on top, followed by the almond flour.
    11.  Bake for 15-20 minutes, or until the surface is crisped and golden brown.

    Notes

    The scale up function does not change the gram measurements.

    Nutrition

    • Serving Size: About ⅓ a Cup
    • Calories: 239
    • Fat: 19
    • Carbohydrates: 4
    • Fiber: 1
    • Protein: 14.4.

    Keywords: Keto tuna casserole, tuna casserole keto, keto casserole recipes, keto tuna fish casserole, cheesy tuna casserole, low carb tuna casserole, keto casseroles, how to make keto tuna casserole, keto tuna casserole recipe, recipes for keto casserole, tuna casserole, recipe for tuna casserole, recipes for casseroles, casserole recipes, tuna recipes, tuna fish recipes, recipes with tuna, keto casserole dish, casserole dinner, low carb casseroles, low carb casserole recipes, casserole low carb, casseroles keto,

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    Reader Interactions

    Comments

    1. Reba

      August 08, 2021 at 8:33 am

      This was delicious!! My family really enjoyed the casserole.

      ★★★★★

      Reply
    2. Pam

      August 11, 2021 at 4:58 pm

      This is a very easy and delicious low carb casserole recipe.

      ★★★★★

      Reply
      • Amy B

        December 05, 2021 at 4:57 pm

        Oh my gosh…. The absolute most delicious tuna casserole EVER! My adult son who claims he doesn’t like onions or spinach ate half the casserole in one sitting. I didn’t even make it for him. I wouldn’t change a thing about this. Amazing

        ★★★★★

        Reply
        • Brendan Cunningham

          December 08, 2021 at 5:48 pm

          So glad you two liked it!

          Reply
    3. Paula

      September 12, 2021 at 8:18 pm

      My favorite keto casserole that I have tried! Delicious!!

      ★★★★★

      Reply
    4. Courtney

      September 14, 2021 at 4:55 pm

      Super delicious casserole recipe! Had a great balance of textures and falvors.

      ★★★★★

      Reply
    5. Meggie

      October 17, 2021 at 9:33 pm

      Great casserole for keto. Family loved it too!

      ★★★★★

      Reply
    6. Trev

      October 21, 2021 at 6:23 pm

      Everything about this recipe is a plus. It was easy, fairly quick, and the casserole turned out perfect.

      ★★★★★

      Reply
    7. Betty

      October 26, 2021 at 6:55 pm

      Loved it. Will make again and I recommend it.

      ★★★★★

      Reply
    8. Miranda T

      October 28, 2021 at 5:49 pm

      This is as good as it gets for a keto casserole1

      ★★★★★

      Reply
    9. Pauline

      October 29, 2021 at 3:48 pm

      Really liked this recipe, I am going to make it again.

      ★★★★★

      Reply
    10. Karen

      October 30, 2021 at 9:43 pm

      My family loved this.

      ★★★★★

      Reply
    11. Bryar

      November 01, 2021 at 6:45 pm

      Tasted excellent!

      ★★★★★

      Reply
    12. Herrine

      November 01, 2021 at 8:41 pm

      Made this for our Sunday family dinner, and had no leftovers. This recipe is 💯

      ★★★★★

      Reply
    13. Neil

      November 02, 2021 at 7:07 pm

      My family (kids included) like this a lot!

      ★★★★★

      Reply
    14. Sally

      November 05, 2021 at 9:16 am

      If anyone wants a easy recipe that will feed a few people this tuna casserole is a great make!

      ★★★★★

      Reply
    15. Kaira

      November 08, 2021 at 2:29 pm

      The crispy top and cheesy flavor is delightful.

      ★★★★★

      Reply
    16. Maddy

      November 09, 2021 at 2:28 pm

      It was easy to make and tasted tasty!

      ★★★★★

      Reply
      • Brendan Cunningham

        November 09, 2021 at 7:32 pm

        Glad you liked the recipe!

        Reply
    17. Madeline

      November 10, 2021 at 8:53 am

      Wonderfully done casserole!

      ★★★★★

      Reply
    18. AG

      November 12, 2021 at 10:06 am

      I love that this uses almond flour to create the crunch. I can't stand recipes that only use pork rinds!

      ★★★★★

      Reply
    19. Jules

      November 16, 2021 at 8:24 pm

      Probably the best dinner that I have made so far on keto.

      ★★★★★

      Reply
    20. Tim

      November 20, 2021 at 3:01 pm

      The cheesiness and crunch this casserole has is incredible.

      ★★★★★

      Reply
    21. Jamie

      November 22, 2021 at 7:45 pm

      I ended up making this over the weekend and my family loved it!!

      ★★★★★

      Reply
    22. Juliette

      November 23, 2021 at 7:59 pm

      One of the best kept casseroles I’ve made.

      ★★★★★

      Reply
    23. Sally

      November 23, 2021 at 9:32 pm

      I really enjoy this for dinner!

      ★★★★★

      Reply
    24. Julie

      November 29, 2021 at 9:57 am

      I'm not even a big tuna fan and I thoroughly enjoyed this casserole.

      ★★★★★

      Reply
    25. Liz

      December 01, 2021 at 7:06 pm

      My go to dinner recipe lately I really like this casserole.

      ★★★★★

      Reply
    26. Madeline

      December 17, 2021 at 2:58 pm

      10 out of 10

      ★★★★★

      Reply
    27. Joyce K

      January 04, 2022 at 7:36 am

      Wow was this ever good! After reading other's comments I felt I had to make this casserole and I was not disappointed. Not only is it easy to throw together in a few minutes but the flavors are amazing! I used frozen spinach as it is what I had on hand but otherwise followed the recipe. It is so good and flavorful. I know this will be on my dinner rotation often.

      ★★★★★

      Reply
    28. Kelly L.

      January 04, 2022 at 1:27 pm

      Actually my family's favorite keto dinner recipe that I have made so far. It's a keeper!

      ★★★★★

      Reply
    29. Kendall

      January 05, 2022 at 11:43 am

      Very good casserole that doesn't taste low carb.

      ★★★★★

      Reply
    30. Andy

      January 06, 2022 at 9:08 pm

      i don't like mushrooms so I left them out but this was very very good.

      ★★★★★

      Reply
    31. Chrissy

      January 09, 2022 at 8:39 pm

      Wow it was a good one.

      ★★★★★

      Reply
    32. Lauren

      January 12, 2022 at 11:58 am

      This is my fav keto dinner!

      ★★★★★

      Reply
    33. Mike

      January 18, 2022 at 9:09 am

      Excellent casserole!

      ★★★★★

      Reply
    34. Tess

      January 18, 2022 at 5:03 pm

      Hi ya'll! Make this if you want a big dinner your family can eat. Mine loved it and said they wouldn't have know it was keto!

      ★★★★★

      Reply
    35. Marcie

      January 19, 2022 at 12:52 pm

      This was splendid.

      ★★★★★

      Reply
    36. Pam

      January 23, 2022 at 9:15 am

      Better than expected. A delicious casserole.

      ★★★★★

      Reply
    37. Zalinda

      January 23, 2022 at 12:42 pm

      Is it possible to use yellow fin tuna in olive oil for this? Our tuna in cans is not the best here in Norway.

      Reply
      • Brendan Cunningham

        January 24, 2022 at 10:16 pm

        Hi Zalinda, yes that should work great!

        Reply
    38. Parker

      January 25, 2022 at 1:01 pm

      Gave it a try and to my surprise my family loved it!!

      ★★★★★

      Reply
    39. Marie

      February 04, 2022 at 12:52 pm

      Excellent!

      ★★★★★

      Reply
    40. Susan

      February 12, 2022 at 2:24 pm

      Super tasty!

      ★★★★★

      Reply
    41. Amy

      April 01, 2022 at 11:02 am

      WOW!!!
      My usual tuna casserole is loaded with noodles, and my kids didn't usually like it.
      I didn't even miss the noodles with this recipe and my kids all gave 2 thumbs up, asking for seconds.
      I upped the recipe to the 2x for my family of 5, it was just hardly enough. Next time I think I'll up it to 3x.

      ★★★★★

      Reply
      • Brendan Cunningham

        April 02, 2022 at 9:31 am

        That's great!! We're so happy everyone liked it 🙂

        Reply

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