How long should the casserole sit overnight before baking?

For best results, your overnight breakfast casserole should rest for at least 6 hours in the fridge after assembling. You can prep it up to 24 hours ahead of time for a truly convenient make-ahead breakfast.

Can I assemble the casserole and bake it right away instead of overnight?

Yes — you can bake it without chilling overnight, but you'll likely miss out on that rich custardy texture and deep flavor that soaking overnight provides. For full flavor and the perfect set, the overnight rest really makes a difference.

What’s the best type of bread to use in an overnight breakfast casserole?

A day-old sandwich bread or cubed French bread works ideally because it soaks up the egg mixture without turning mushy. Avoid very fresh or super dense bread; the goal is balance between moisture absorption and structure.

Can I freeze leftovers of this breakfast casserole?

Absolutely — once fully baked and cooled, wrap tightly and freeze for up to 2 months. Thaw overnight in the refrigerator and reheat in the oven at about 350 °F until warm throughout for best texture.

Overnight Breakfast Casserole – Easy, Cozy Make-Ahead Comfort

Description

An easy, comforting make-ahead dish perfect for mornings or gatherings, this Overnight Breakfast Casserole combines eggs, sausage, bread, and cheese into a golden, hearty bake.

Ingredients

Scale

1 ½ pounds breakfast sausage, cooked and crumbled
8 large eggs
2 cups whole milk
6 cups day-old bread, cubed
2 cups shredded cheddar cheese
½ cup diced bell peppers
¼ cup chopped green onions
1 teaspoon dry mustard powder
Salt and pepper to taste
Butter or spray for greasing

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Instructions

Cook sausage until browned; drain.
Grease a 9×13-inch baking dish and add cubed bread.
Layer cooked sausage, bell peppers, and green onions over bread.
Whisk eggs, milk, mustard, salt, and pepper; pour evenly over layers.
Top with shredded cheese.
Cover and refrigerate overnight.
Next morning, let rest at room temperature 20 minutes.
Bake uncovered at 350°F for 45–55 minutes until golden and set.
Cool 10 minutes before slicing and serving.

Notes

Use day-old bread for best texture.
Substitute bacon, ham, or turkey sausage as desired.
Freeze leftovers up to 2 months and reheat at 350°F.
Add spinach or mushrooms for extra flavor.

Prep Time: 20 minutes
Cook Time: 55 minutes
Category: Breakfast
Method: Baking
Cuisine: American