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This Overnight Breakfast Sausage Casserole can be prepped and made the night before! Store it in your fridge overnight and bake the next morning. Quick, easy, and loaded with sausage, peppers, onions, toasted bread, eggs, milk, and of course, cheese! showmetheyummy.com #overnightbreakfastcasserole #breakfast #casserole #sausage #eggs #cheese #bread
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4.75 from 4 votes

Overnight Breakfast Sausage Casserole

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!
Prep Time20 mins
Cook Time1 hr 30 mins
Total Time1 hr 50 mins
Course: Breakfast
Cuisine: American
Keyword: easy prep, overnight, sausage
Servings: 16 people
Calories: 212kcal


  • 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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*It’s really important that you drain the sausage/peppers/onions really well.
**I needed the full 90 minute bake time, but you may not depending on your oven, bread, casserole dish, etc.
***I’ve made this without the peppers and onions if you’re not a fan. It’s GREAT. I'd just add some garlic/onion powder/paprika to the mixture and you’ll probably bake it for a good 30 minutes less, because the peppers and onions add so much moisture.


Calories: 212kcal | Carbohydrates: 7g | Protein: 12g | Fat: 14g | Saturated Fat: 6g | Cholesterol: 104mg | Sodium: 420mg | Potassium: 226mg | Fiber: 1g | Sugar: 2g | Vitamin A: 585IU | Vitamin C: 16.3mg | Calcium: 162mg | Iron: 1.1mg