This Overnight Breakfast Sausage Casserole can be prepped and made the night before! It’s quick, easy, cheesy, and loaded with breakfast sausage, veggies, egg, toasted bread, and more!
Savory breakfast lovers, this overnight breakfast casserole is for you! Toasty bread, savory sausage, tender veggies, gooey cheese…breakfast is sounding SO GOOD!
- Breakfast Sausage – you can use hot, sweet, or any flavor you like. Anything goes!
- Yellow Onion, Red Bell Pepper, and Green Bell Pepper – a classic, slightly sweet veggie blend to add color and texture to the casserole.
- Garlic – adds a subtle flavor kick.
- Salt and Pepper – brings out flavor and adds a touch of heat.
- Whole Wheat Sandwich Bread – I like to use whole wheat bread cause I think it holds up nicely in the casserole but any bread will work.
- Colby-Jack Cheese – or any of your favorite cheeses!
- Eggs – binds the casserole together so it can hold its shape.
- Skim Milk – or any other milk you have on hand.
- Green Onions – for topping.
How to make
This overnight breakfast casserole is perfect for holiday brunches or any brunch that you want to prep the night before!
- Cook sausage in a large non-stick sauté pan, breaking it up as you go, until it’s cooked through. Drain well then set aside to cool.
- In the same pan, cook onion, peppers, garlic, salt, and pepper until the peppers are tender. Drain then set aside to cool.
- Add toasted and cubed bread, cooled breakfast sausage, cooled peppers/onions, and 4 ounces of shredded cheese into a greased baking dish. Stir to combine.
- In a large bowl, whisk together eggs and milk until fully combined.
- Pour the egg mixture evenly over the bread/sausage mixture in the baking dish. Don’t stir.
- Cover with saran wrap and store in the fridge overnight (or for at least 8 hours.)
- After 8 hours, remove saran wrap, top with remaining 4 ounces of cheese, and let sit at room temperature while you preheat the oven to 375ºF.
- Cover casserole with tin foil then bake for 60-75 minutes. Uncover and bake for an additional 15 minutes or until the eggs have set and the cheese is melted.
- Let sit for 10 minutes then serve and enjoy!
What bread to use
I use whole wheat sandwich bread toasted and then cubed into smaller pieces but whatever bread you have on hand will work just fine!
Try Italian or French bread, croissants, or even cubed bagels!
Do you cover breakfast casserole when baking?
Yes! Covering the casserole with foil as it bakes initially gives it time to heat all the way through without the top burning.
Once it’s cooked for the first 60-75 minutes, you can remove the foil and bake for another 15 so the top gets a little toasty and the cheese can melt.
Why is my overnight breakfast casserole soggy?
There may be a couple of reasons your casserole came out slightly soggy.
- You didn’t pre-cook the veggies. As they cook, veggies add a lot of moisture. Pre-cooking them allows that moisture to release outside of the casserole. If you put them into the casserole raw, they’ll release the moisture as it bakes and make the bread soggy.
- You didn’t drain the sausage/veggies. Make sure you drain the grease from the sausage and the moisture from the veggies before adding them into the casserole.
- The cook time was too short. The long cook time bakes away any extra moisture. If the casserole is soggy, you may want to try and bake just a little bit longer to remove any excess liquid.
I love this overnight breakfast casserole as-is but it’s also pretty darn customizable so make it to fit your tastes!
- Add other meat. Try ham, chorizo, or bacon.
- Add other veggies. Asparagus, artichokes, mushrooms, diced potatoes, etc. Make sure you cook whatever veggies you use before putting them in the casserole.
- Use another bread. French bread, Italian bread, croissants, or even cubed bagels.
- Try other cheeses. Try goat cheese, cheddar cheese, mozzarella, gouda, you name it.
What to serve with breakfast casserole
Serve this sausage breakfast casserole alongside more of your favorite breakfast dishes!
Can you make breakfast casserole ahead of time?
Heck yes! In fact, this breakfast casserole is made ahead of time…hence the name overnight breakfast casserole!
You can let the breakfast casserole sit in the fridge for up to 18 hours before baking. You can also cover it and store it in the freezer for up to 2 months before baking. Then, when you’re ready to eat, thaw overnight in the fridge and bake as directed.
How to store
Store leftover baked casserole in an airtight container in the fridge for 3-4 days or in the freezer for up to 1-2 months.
To reheat, thaw in the fridge if frozen and bake at 350ºF for 30 minutes or until heated through. You can also microwave individual slices if preferred.
Overnight Breakfast Sausage Casserole
Equipment for this recipe
- 1 pound breakfast sausage cooked and drained
- 1 small yellow onion diced
- 1 red bell pepper diced
- 1 green bell pepper diced
- 4 cloves garlic minced or pressed
- 1/2 teaspoon salt plus more to taste (I used 1 teaspoon)
- 1/2 teaspoon pepper
- 6 slices whole wheat sandwich bread toasted and cubed - each slice cubed into 9 pieces (whatever bread you have on hand is fine)
- 1 (8 oz) block colby-jack cheese shredded and divided (whatever you have on hand is fine) more to taste, I used more on top
- 6 large eggs
- 2 cups skim milk whatever you have on hand is fine
- Green onions for topping
- Grease a 9x13 inch baking pan with cooking spray. Set aside.
- Cook sausage in a large non-stick sauté pan, breaking it up as you go, over medium heat, until the sausage has cooked through.
- Drain WELL and set aside to cool.
- Cook onion, peppers, garlic, salt, and pepper, in the same large non-stick sauté pan over medium heat, until the peppers are tender and cooked to your liking.
- Taste and re-season, if necessary.
- Drain WELL and set aside to cool slightly.
- Add toasted and cubed bread, cooled breakfast sausage, cooled peppers/onions, and 4 oz shredded cheese into the prepared pan.
- Stir to combine.
- In a large bowl, whisk together eggs and milk until the mixture is fully combined.
- Pour mixture evenly over the bread/sausage, etc. mixture in the pan. (No need to stir.)
- Cover with saran wrap and store in the fridge overnight (or at least 8 hours).
- Preheat oven to 375 degrees F (let the casserole sit at room temperature while oven is preheating).
- Remove saran wrap from casserole, top with remaining 4 oz cheese, then cover with tin foil (that’s been greased with cooking spray) .
- Bake in preheated oven for 60-75 minutes.
- Uncover, then bake an additional 15 minutes (if necessary), or until the eggs have set and the cheese is melted.
- Let sit for 10 minutes.
- Serve with green onions and enjoy!
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*Note: Nutrition information is estimated and varies based on products used.