I’m happy to share my version of this Breakfast Casserole—a savory, customizable egg bake layered over bread or potatoes with your favorite veggies, meats, and cheese. It’s the perfect dish for breakfast, brunch, or even dinner, and it’s ideal for assembling in advance.

Easy Make-Ahead Breakfast Casserole

Why I’ll Love This Recipe

I love this casserole because I can prep it the night before and simply bake it the next morning. I mix vibrant vegetables, cooked meat, eggs, cheese, and bread (or potatoes) to create a hearty bake that’s flexible and forgiving. It feeds a crowd and makes great leftovers, too.

Ingredients

(Here’s a tip: Check out the full list of ingredients and measurements in the recipe card below.)

Vegetables (e.g., sautéed bell peppers, spinach, mushrooms, onions)
Meat (optional: cooked sausage, ham, or extra vegetables if vegetarian)
Bread cubes (from crusty day‑old bread) or hash brown potatoes
Eggs
Milk or half‑and‑half
Shredded cheese (e.g., cheddar, Swiss, or Parmesan)
Flavorings: garlic, onion, Italian seasoning, ground mustard, salt, pepper

Directions

I sauté chosen vegetables (and meat, if using) in a skillet until flavors meld and veggies soften.
I layer chunks of bread or hash browns in a greased baking dish.
I whisk together eggs, milk (or half‑and‑half), cheese, and seasonings.
I pour the egg mixture evenly over the bread or potato base and gently press so it soaks through.
I optionally cover and refrigerate the assembled casserole for up to 24 hours.
When it’s time to bake, I let it come to room temperature as the oven preheats to about 375 °F (190 °C).
I bake until the egg is set, golden on top, and cooked through—usually around 45 minutes.

Servings and timing

Prep time: ~20–30 minutes, depending on add-ins and chopping
Make-ahead rest: optional refrigeration for up to 24 hours
Bake time: around 45 minutes
Total time: ~1 hour (including bake and resting time)
Serves: 8–12 people, depending on dish size and portioning

Variations

I mix peppers, spinach, mushrooms, or kale to keep it colorful and nutrient-rich.
I add cooked breakfast sausage, or use crusty bagel cubes for more flavor—Sally’s Everything Bagel Breakfast Casserole is a reader favorite.
I make vegetarian versions by skipping meat and adding more veggies or cheese.
I use hash browns or potato cubes instead of bread—either absorbs the egg custard well and keeps the casserole close in texture to a strata.

Storage/reheating

I refrigerate leftover slices in an airtight container for up to 3–4 days—flavors meld and reheat well.
To reheat, I warm them in the oven until heated through or microwave individual servings.
I freeze cooled portions or the assembled casserole before baking for up to 2 months—just thaw overnight and bake as directed.

FAQs

Can I assemble this casserole entirely the night before?

Yes—I often layer it completely and refrigerate overnight. I let it sit out briefly before baking to ensure even cooking.

Do I have to use bread as the base?

No—bread adds structure and soaks up moisture, but hash brown potatoes work equally well for a softer but flavorful texture.

Can I customize the mix-ins to what I have on hand?

Absolutely. Vegetables like peppers, mushrooms, spinach, and meats like sausage are all flexible — this recipe thrives on adaptation.

Will it be soggy if I leave it overnight?

Not if you use sturdy crusty bread or even cubed bagels that absorb moisture well. Letting it sit in the fridge helps flavors meld without turning it soggy.

How do I know when it’s baked through?

The casserole is done when the eggs are set and no longer runny, the top is lightly golden, and an inserted knife comes out clean. Usually about 45 minutes at 375 °F.

Conclusion

I adore this Easy Make-Ahead Breakfast Casserole because it’s comforting, flexible, and stress-free to prep ahead. Whether I’m preparing for a crowd or simplifying weekday mornings, this casserole lets me serve something hearty and delicious with minimal effort.