The BEST French Onion Chicken Casserole Recipe

This French onion chicken casserole recipe is jam-packed with flavor. The caramelized onions, seasoned chicken breasts, and mozzarella cheese all blend together in a French onion soup mix to create a unique and addictive casserole that everyone will love. And, to top it all off, it's actually really easy to make in just a few simple steps!

My Take On French Onion Chicken Casserole

I've made a ton of chicken casseroles lately, and I think this one is honestly one of the best chicken casserole recipes out there.

It just has the perfect blend of sweet and savory flavors that you won't be able to resist. I mean, there's just tons of sweet tangy yumminess from the onions, rich meaty deliciousness from the chicken, and umami goodness from the soup broth. Gah, it's just so I could eat it every night for dinner!

It's basically what would happen if French onion soup and chicken made a baby, and that baby was a casserole - a very, very delicious casserole. So, if you're a classic French onion soup lover, then this French onion chicken casserole is definitely for you.

The best part about this recipe, though, isn't how delicious it is. I think it's how easy it is to make. You just cook everything in one pan on the stovetop, then transfer it to a casserole dish, and dinner will be on the table in under 30 minutes!

Oh, and while the casserole is baking, you can whip up this air fryer garlic bread recipe to dip into the soup for that classic French onion soup experience. Or, for the ultimate French onion soup vibes, make my French onion pasta.

Ingredients

Now, another reason to love this recipe is that you only need a little more than a handful of ingredients to bring it together. And if you have the chicken and soup, I can almost guarantee you have everything else you need at home already!

Anyway, here's what you'll need to make this French onion chicken casserole:

• 2 chicken breasts, skinless, boneless, cubed
• ⅛ tsp. paprika 
• ⅛ tsp. garlic powder 
• ⅛ tsp. salt
• 2 tbsp. butter 
• 1 cup onion, sliced
• 2 cups French onion soup mix
• ½ cup mozzarella
• 2 slices of toasted bread cut into pieces
• Fresh thyme and French fried onions for garnish (optional)

Pretty simple stuff, right?

By the way, if you're headed to the grocery store to pick up chicken, make sure to grab some extra. You can use it to make this Halal Cart chicken over rice next!

Oh, and if you have extra French onion mix, you can use it to make these French onion pork chops.

My Suggestions For Ingredient Substitutions 

While I recommend making this French onion chicken casserole with the ingredients listed above - because it's just so delicious that way - you definitely have a little wiggle room to make some substitutions.

Use Rotisserie Chicken

First off, if you want to speed up this recipe a little bit, you can skip cooking the chicken breast and simply use pre-cooked rotisserie chicken. Just chop the rotisserie chicken meat up, and season it with a little paprika, garlic powder, and salt. Then, continue on with the recipe as is.

Add Some Crunch

Now, if you want to top this casserole off with a little something crunchy, you can sprinkle a few crispy fried onions over the top of your French onion chicken casserole before serving it. The French fried onions add a salty, tasty crunch to the casserole that is just so addictive.

Use Chicken Soup

Now, this may sound counterintuitive, but you can actually use two cups of chicken soup in place of the French onion soup base if you're in a pinch. However, I recommend making 1 ½ cups of caramelized onions to make up for the missing onion flavor in the chicken soup if you do.

By the way, if you're feeling ambitious, you can skip the canned French onion soup and make your own. It is actually pretty easy to make since the soup cooks in the Instant Pot.

Make it Creamy

Everyone loves a creamy chicken casserole, and this recipe can be as creamy as you'd like! Try stirring ½ cup of sour cream into the skillet along with the French onion soup. Whisk the sour cream into the sauce, and you will have the creamy chicken casserole of your dreams!

Add Noodles

If you want to make this casserole even heartier you can add some egg noodles to it. Just add them to the chicken mixture before you bake the casserole.

Change the Cheese

Lastly, if you don't have mozzarella cheese, don't worry! You can definitely change the cheese in this recipe and use what you've got. Gruyere cheese works well, and so does Swiss cheese. You can even try melting some provolone cheese slices over the casserole in the baking dish to get that classic French onion soup taste. And, of course, you can top the baked casserole off with some grated parmesan cheese as well.

How to Make French Onion Chicken Casserole

I already mentioned how easy this recipe is to make, but it really might be the easiest French onion chicken casserole you ever try!

I mean, the whole thing comes together in four simple steps. All you have to do is saute the onions, cook the chicken, simmer the soup, and then bake the casserole. It really doesn't get much simpler than that!

Anyway, let's not waste another second and get into the recipe.

Step 1: Caramelize the Onions

The first part of this recipe will be to caramelize the onions, but before you do that, you'll want to preheat your oven to 350°F (180°C).

Anyway, now you'll want to take out a large deep skillet, put it over medium-high heat, and add the butter to it. Once the butter melts and coats that pan, you can add the sliced onions to it and cook them until they're slightly softened, translucent, and a little bit browned. Then, you can put the sauteed onions on a plate and set them aside for later.

Step 2: Cook the Chicken

Now it's time to cook the chicken. Start by slicing the chicken into cubes if you haven't done so already. Then, add the sliced chicken breasts to a bowl along with the paprika, garlic powder, and salt, and mix the chicken around to coat it in the seasonings.

Next, add a little more oil to the hot skillet and add the seasoned chicken breasts to it. Now you can cook the chicken for about 5-7 minutes on both sides or until the chicken breasts are golden brown.

Step 3: Make the Casserole

Now that the chicken is cooked, you can add the onions back to the pan and pour in the French onion soup mix. Then, you'll want to let the cooked chicken and onions simmer in the soup for about 2-3 minuntes just to allow those flavors to infuse into the broth.

Then, after a couple of minutes have passed, you can pour the chicken and onion soup mixture into an oven-safe baking dish and top it off with some pieces of toast and cheese.

Step 4: Bake the Casserole

Finally, you can pop your French onion soup casserole into the oven and bake it for about 10-15 minutes - or until the shredded cheese is melted and bubbly.

Then, once it bakes, you can serve it with some fresh thyme on top along with a few delicious French fried onions. Atleast that's what we like to top the casserole with at our house. Enjoy!

How I Recommend Storing French Onion Chicken Casserole

This French onion chicken casserole recipe is pretty big and makes about 4 servings. So, it's really perfect for a family dinner or to save and eat as leftovers for the week. 

Speaking of leftovers, if you end up with some, you can store them in an airtight container and they'll stay good in the fridge for about 3-4 days. You can also simply wrap the casserole baking dish in plastic wrap, sealing it tightly, or place a lid on the baking dish if you have one, and store it in any of those ways as well. This is an easy way to store the cooked chicken casserole and not make any new dishes to wash!

How I Reheat French Onion Chicken Casserole

I love reheating this French onion chicken casserole for some delicious leftovers.

The best way to reheat the casserole is to put everything back in a casserole dish and heat it in the oven at 350°F for about 10 minutes - or until the cheese melts and the French onion soup mix is warmed through. However, an equally delicious way to reheat it is in a pot set over medium-high heat on the stove.

Alternatively, if you'd like to reheat just a single portion of the casserole, you can simply microwave it in 30-second increments until warm. For what it's worth when I reheat the soup this way, I like to add a couple of slices of mozzarella - or provolone - cheese to the top during the last couple of cooking intervals.

Also, don't forget to top it off with some more French's crispy fried onions when you reheat it too.

My Final Thoughts

Well, that's how to make a French onion chicken casserole!

This chicken casserole recipe is truly like no other. From the flavorful French onion soup mix and caramelized onions to the tender chicken and glorious melted cheese, it's just so, so good.

If you have any French onion soup lovers in your life, you have to make this casserole recipe for them. It's sure to become their new favorite casserole.

Anyway, I hope you enjoy this casserole recipe as much as I/we do.

As always, if you give this recipe a try, leave a comment below and let me know how it went!

More Casserole Recipes

If you loved this French onion chicken casserole recipe and are looking for more easy casserole recipes to try, we have a bunch on the blog you can make next!

Here are some more casserole recipes I think you'll love:

• Ruben casserole
• Pulled pork casserole
• Chile relleno casserole
• Buffalo chicken casserole
• Salmon casserole
• Chicken cordon bleu casserole

Oh, and for even more drool-worthy recipes, be sure to follow us on YouTube, TikTok, and Instagram. We post new ones on them every day!