This comforting sausage egg casserole is our absolute favorite brunch recipe. It’s cheesy, flavorful, and super easy to make!
It’s really versatile, too. It works as both a fancy (but hands off, because you prep it the night before) brunch recipe or as a weekly meal-prep breakfast.
Thank you to The Incredible Egg for sponsoring this delicious recipe post!
Matt and I first enjoyed this egg casserole with sausage and cheese over Easter this year just the two of us, and the leftovers were fantastic (fannetastic, I mean!) as an easy lunch or breakfast the rest of the week, too.
It’s delicious, filling, and savory, and contains protein thanks to the egg and sausage so you won’t be hungry again a second later like with some breakfast casseroles.
Overnight Breakfast Casserole with Sausage
This tasty breakfast bake is packed with nutritious eggs, whole wheat bread, cheddar cheese, sausage, and veggies. And, it can be made ahead of time, so all you have to do in the morning is pop it in the oven. Easy peasy.
This recipe calls for spinach and bell pepper, but you can use a variety of veggies! Asparagus, broccoli, mushrooms, and/or sweet potatoes would all be delicious. (Just keep in mind that heartier veggies like sweet potatoes should be cooked or roasted beforehand).
Sausage Egg Casserole Ingredients
To make this sausage egg casserole, you’ll need:
- whole grain/wheat bread
- Cheddar cheese (I recommend sharp for more flavor!)
- sausage (you can buy pre-cooked or raw, but just make sure it’s cooked before adding it to the casserole to bake)
- whole milk
- Dijon mustard
- fresh spinach (you can also use canned or frozen spinach, but be sure to squeeze out as much moisture from the spinach as possible before adding it to the casserole. Too much moisture can make the whole thing soggy!)
- bell pepper
The eggs, of course, are the star in this recipe, and for good reason: did you know that eggs are an excellent or good source of eight essential nutrients?
Eggs provide an excellent source of vitamin B12, biotin (B7), iodine, selenium, and choline; a good source of high-quality protein, riboflavin (B2) and pantothenic acid (B5); as well as the carotenoids lutein and zeaxanthin (252 mcg). Eggs are also one of the only foods that naturally have vitamin D (1 mcg per large egg), which is critical for building strong bones.
Starting the day with high-quality protein, like eggs, for breakfast can help support muscle and bone health while also helping to provide energy. And at only about 15 cents per serving, eggs are one of the most affordable sources of high-quality protein, so eat up!
By the way – be sure not to toss the yolk because it’s where nearly all the vitamins and minerals of an egg are located, including those I just mentioned! The yolk also has about 40% of the egg’s protein – it’s not only in the egg white like many people believe.
How to Make a Breakfast Casserole
Start by beating your eggs in a bowl. Add the Dijon mustard and milk to the eggs and stir well.
Next, cut up your bread into cubes, chop your spinach, and dice your bell peppers. If using raw sausage, cook that in a skillet over medium-high heat until no longer pink and set aside.
Next, grease a 9×13 baking dish. In the dish, place the bread, sausage, spinach, and diced bell peppers. Pour the egg/milk/mustard mixture over top, then sprinkle it evenly with cheese.
Make sure the bread cubes are pretty evenly well-coated with the egg/milk mixture.
Cover with foil and let sit overnight in the refrigerator. In the morning, bake (uncovered) for 45-50 minutes at 350 degrees F. Then serve!
Does this casserole have to sit overnight?
Allowing the casserole to sit overnight in the fridge lets the bread really soak up the eggs, but you should be fine to bake the casserole the same day, too! I’d say let it sit at room temp for 30 minutes first, if you can.
This quicker method would especially work well with moist sandwich-style bread, which soaks things up more quickly. With drier, bakery-style bread, I’d recommend soaking overnight.
How to Store and Reheat Cooked Sausage Egg Casserole
Either cover your baking dish and store it that way in the fridge, or cut up the leftover casserole into slices and store in an airtight container. Leftovers should last in the fridge for 3-4 days. When reheating, just microwave for 30-60 seconds!
I wouldn’t recommend re-baking the casserole in the oven to reheat it, as the edges would get pretty brown/tough before the middle got heated through. If you’re planning to make ahead for brunch, I’d assemble the night before and bake the morning-of. For meal prep, store leftovers in the fridge and microwave individual portions.
As for freezing, I wouldn’t recommend freezing the end product to store leftovers because it gets pretty mushy and starts to separate. So, this is a recipe that’s best enjoyed either right away or in the few days following it!
I hope you love this recipe as much as my family does! It goes perfectly paired with a latte, or a scone or pastry if you’re feeling fancy. 🙂 You’ll find the full breakfast egg casserole recipe at the bottom of this post. Enjoy!
Looking for more delicious brunch recipes that contain eggs? Check these out:
- Butternut Squash, Prosciutto, and Goat Cheese Strata
- Overnight Crockpot French Toast Casserole
- Easy Savory French Toast
- Healthy Breakfast Tacos with Avocado Crema
- Crustless Quiche Recipe with Veggies & Goat Cheese
- Sheet Pan Eggs with Potatoes & Veggies
- Veggie Egg Casserole (Frittata) Recipe with Smoked Salmon
- Hard Boiled Egg and Cheddar Muffins
- Veggie Scrambled Egg Muffins
- Apple + White Cheddar Omelette
- 8 large eggs (beaten)
- 1 tablespoon dijon mustard
- 2 cups whole milk
- 4 slices of whole grain/wheat bread (cubed)
- 1 cup grated sharp cheddar cheese
- 1 pound of cooked sausage
- 1 cup (tightly packed) fresh spinach (chopped)
- 2 red bell peppers (diced)
- Whisk together the eggs, dijon mustard, and milk.
- Grease a 9x13 baking dish. In the dish, place the bread, sausage, and chopped spinach and bell pepper. Pour the egg/milk/mustard mixture over top, then sprinkle with cheese.
- Cover the dish with foil and let sit in the refrigerator overnight.
- In the morning, bake (uncovered) for 45-50 minutes at 350 degrees F.