The BEST Overnight Egg Casserole (Sausage, Egg, and Cheese)

This overnight egg casserole is going to change the way you do breakfast. This recipe combines savory sausage with cheesy eggs and fluffy bread to make an addictive breakfast casserole everyone is sure to love. And best of all, everything comes together in just 10 minutes!

The Best Breakfast Casserole

When it comes to breakfast casseroles, it doesn't get much better than this make-ahead egg bake. It has the perfect combination of flavors and it's made with simple breakfast ingredients like eggs, cheddar cheese, sausage, and bread.

The end result is a savory, cheesy, hearty egg breakfast casserole your family won't be able to get enough of! Atleast mine can't. Plus, it's endlessly customizable, too, so you can make this casserole again and again without ever getting bored.

The results are seriously out-of-this-world delicious for how easy this recipe is. In fact, everything comes together the night before, so all you have to do is grab it out of the fridge and pop it in the oven for the perfect make-ahead breakfast.

By the way, since the oven does most of the heavy lifting, you'll have plenty of time to work on some breakfast sides like this million dollar bacon and these air fryer hash browns.

Ingredients

As I mentioned earlier, the ingredient list for this overnight egg casserole is really simple. In fact, if you love breakfast as much as I do, then I'm willing to bet you already have most - if not all - of the ingredients you'll need for it on hand already!

Anyway, here's what you'll need:

• 1lb. mild sausage, removed from the casing
• 6 medium eggs
• 2 cups milk
• Salt and pepper, to taste
• 1 teaspoon whole-grain mustard
• 1 cup cheddar cheese, shredded
• 6 slices of bread, cubed

Pretty simple stuff, right?

Oh, and you can use basically all of these same ingredients to make this Christmas breakfast casserole, Bisquick breakfast casserole, and breakfast casserole with ham as well. So if you're craving more easy breakfast casseroles, definitely check those out next!

Ingredient Substitutions and Suggestions

When I make this recipe, I always use the ingredients listed above since I just think it tastes best that way. However, you definitely can make some adjustments to it if you'd like to put your own spin on it.

First, this recipe calls for breakfast sausage, but if you want to make it more savory, you can use pork sausage, Italian sausage, or herbed chicken sausage. Just make sure you remove the casing if it has one.

Now, this recipe is kept pretty simple, but if you want to add even more flavor to it, then you can play around with adding some extra ingredients. Things like diced red bell pepper, sliced mushrooms, green onions, crispy bacon, hash browns, and extra cheese can all boost the flavor in this casserole.

How To Make Overnight Egg Casserole

Now it's time for the fun part - it's time to make the casserole!

As I mentioned a few times, it's couldn't be easier to make this overnight egg casserole. And as the name suggests, this recipe requires you to make the egg casserole ahead of time and let it refrigerate overnight, so keep that in mind before making it.

Anyway, let's not waste any more time and get cooking.

Step 1: Cook The Sausage

First, you'll want to coat a 9-inch casserole dish with some butter or nonstick cooking spray.

Then, you can take out a large skillet and set it over medium-high heat. Once the pan is hot, add the pork sausage and cook it for a few minutes, breaking it apart until it's browned and fully cooked.

Step 2: Make The Egg Mixture

Up next, grab a large bowl and whisk together the eggs with milk, salt, pepper, and whole-grain mustard. As soon as everything is fully mixed together, you can stir in the shredded cheddar cheese.

Step 3: Assemble The Casserole

Now that the filling is good to go, it's time to assemble the casserole. First, you'll want to place the cubed bread into the prepared baking dish, then add the browned sausage and pour the egg mixture on top.

Then, you can transfer the prepared breakfast casserole into the fridge and let it chill overnight. 

Step 4: Bake The Casserole

The next day whenever you're ready to eat this delicious casserole, you'll want to preheat the oven to 350°F (180°C). Then, you can take the casserole out of the fridge while the oven preheats.

Once the oven is heated, you can put the casserole in it and let it bake for about 45 minutes. When the time is up, allow the finished casserole to cool for 5 minutes before slicing and serving.

Enjoy!

How To Store Egg Casserole

This recipe for overnight egg casserole makes 6 servings, but honestly, it's so good that I wouldn't expect to end up with any leftovers. In fact, I usually make two of these casseroles since everyone always wants two or three servings!

Now, if you end up with leftovers, you can store them in an airtight container or just put the lid on your casserole dish if you have one. Stored this way, you can keep the baked casserole in the fridge for 3-4 days.

Alternatively, if you want your leftovers to last even longer, you can store them in a freezer-safe bag and freeze the breakfast casserole for up to 2 months.

How To Reheat Egg Casserole

When you're ready to enjoy your breakfast casserole again, it's definitely best reheated.

To reheat your casserole, I suggest transferring it back to the casserole dish and heating it in the oven at 350°F for about 10 minutes or until the cheese melts and it reaches your desired temperature.

However, if you're just trying to reheat a single serving, you can just pop it in the microwave and heat it in 30-second intervals until it's fully reheated.

FAQs About This Breakfast Casserole Recipe

Why do you refrigerate egg casserole overnight?

You refrigerate the egg casserole overnight so the bread can soak up some of the egg mixtures. It allows the bread to stay tender instead of crisping up too much when it bakes the next day. 

How long can you refrigerate an egg casserole before baking?

You can refrigerate your egg casserole for up to 24 hours before baking. The least amount of time I'd suggest refrigerating it is for 1 hour. So if you want to make this casserole as soon as possible, you can bake it the same day you prepare it.

Can egg casserole sit out overnight?

No, you do not want to let egg casserole sit out overnight. Since it has uncooked meat in it, you'll want to make sure that you refrigerate it overnight.

Wrapping It Up

Well, that's how to make overnight egg casserole!

This easy egg bake is about as quick, easy, and convenient as making breakfast for a big group gets. Plus, it's always a huge hit too.

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

As always, if you give this recipe a try, let us know how it goes in the comments below.

More Casserole Recipes

If you liked this easy breakfast casserole recipe, we have plenty more casseroles on the blog for you to try next!

Check these out:

• Cracker Barrel hashbrown casserole
• Sausage cream cheese casserole
• Mexican breakfast casserole
• Loaded cauliflower casserole
• Mexican casserole
• Chicken divan
• Cheeseburger casserole
• Hashbrown egg casserole

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