Can I make this casserole without the bread layer?

Absolutely! The bread adds nice texture and helps absorb moisture, but you can omit it for a more frittata-like dish. Alternatively, substitute frozen hash browns (about 3 cups) for a gluten-free option with a different but equally delicious texture.

Why is my breakfast casserole watery?

This typically happens when vegetables release too much moisture during baking. Make sure to pre-cook vegetables thoroughly and drain any excess liquid before adding them to the casserole. Also, using stale or toasted bread helps absorb moisture better than fresh bread.

Can I use egg whites or an egg substitute instead of whole eggs?

Yes, though the texture and richness will be different. For a lower-cholesterol version, substitute half the eggs with egg whites (2 whites = 1 whole egg). Commercial egg substitutes also work following package conversion guidelines, but expect a lighter final dish.

How do I know when the casserole is fully cooked?

The casserole should be golden brown on top with crispy edges. The center should be set but might have a slight jiggle - similar to a cheesecake. A toothpick inserted in the center should come out clean without wet egg mixture. If the top browns too quickly before the center is done, cover loosely with foil for the remaining bake time.

Easy Make-Ahead Breakfast Casserole Recipe

Name: Easy Make-Ahead Breakfast Casserole Recipe
Prep time: 20 min
Cook time: 45 min
Total time: 1 h 30 min
Cuisine: American
Ingredients: 4 cups (175g or 6 oz) cubes of crusty bread; 1 teaspoon olive oil; 1 pound ground pork sausage, casings removed; 1 teaspoon dried rosemary or Italian seasoning (optional); 3/4 cup (100g) chopped yellow onion (1/2 of a large onion); 2 garlic cloves, minced; 2 cups (275g or 9–10 oz) chopped bell peppers; 1 cup (100g or 3 oz) sliced mushrooms; 1 cup roughly chopped fresh spinach; 12 large eggs; 1/4 teaspoon salt; 1/8 teaspoon freshly ground black pepper; 2/3 cup (160ml) milk or half-and-half; 1 cup (100g or 3.5 oz) shredded cheddar cheese; Green onions and/or chopped parsley

This Easy Make-Ahead Breakfast Casserole is a game-changer for busy mornings. Packed with savory sausage, colorful vegetables, and fluffy eggs all nestled on a bed of crusty bread, this hearty dish delivers incredible flavor in every bite. The best part? You can prepare it the night before and simply pop it in the oven when you’re ready to enjoy. Perfect for holiday brunches, weekend family gatherings, or meal prepping for the week ahead!

Why You’ll Love This Recipe

Prep Ahead Magic: Assemble everything the night before and wake up to a breakfast that only needs baking – perfect for stress-free mornings and special occasions.
Customizable: This versatile casserole welcomes substitutions based on what you have in your fridge – swap different vegetables, cheeses, or proteins to make it your own.
Family-Friendly: The combination of bread, eggs, cheese, and veggies creates a complete meal that will satisfy everyone around your table.
Balanced Nutrition: Packed with protein from eggs and sausage, plus a rainbow of vegetables for essential vitamins and minerals – it’s a nutritional powerhouse to fuel your day.

Ingredients You’ll Need

Crusty bread: Forms the foundation of the casserole, soaking up all the delicious flavors. The staler the bread, the better it will absorb the egg mixture without becoming soggy.
Ground pork sausage: Provides rich savory flavor and hearty protein. Its natural fats add incredible taste throughout the dish.
Dried rosemary or Italian seasoning: Optional but highly recommended for adding depth and aromatic notes that elevate the entire casserole.
Yellow onion: Creates a flavor foundation and adds natural sweetness when cooked.
Garlic: Essential for adding that unmistakable aromatic punch that makes everything taste better.
Bell peppers: Contribute vibrant color, sweet flavor, and a pleasant texture contrast to the soft eggs and bread.
Mushrooms: Bring an earthy, meaty element that adds wonderful umami depth.
Fresh spinach: Provides nutrition and color while practically disappearing into the casserole – perfect for vegetable skeptics!
Eggs: The star ingredient that binds everything together into a delicious, protein-rich dish.
Milk or half-and-half: Creates that custard-like texture that makes breakfast casseroles so irresistible.
Cheddar cheese: Adds rich flavor and that wonderful gooey, melty texture we all love in a breakfast bake.
Salt and pepper: Simple seasonings that enhance all the other flavors in the dish.

Note: You’ll find the complete list of ingredients, along with their exact measurements, in the printable recipe card at the bottom of this post.

Variations

Don’t be afraid to customize this casserole to suit your preferences or use up ingredients in your refrigerator:

Bread Alternatives: Switch the bread for frozen hash browns (no need to thaw) for a gluten-free option that creates a completely different but equally delicious texture.
Protein Swaps: Replace sausage with crispy bacon, diced ham, or shredded rotisserie chicken for a different flavor profile.
Cheese Adventures: Try pepper jack for heat, feta for tang, or smoked gouda for depth – or use a combination of your favorites for a more complex flavor.
Vegetable Medley: Swap in broccoli, zucchini, asparagus, or any vegetables you need to use up – just make sure to pre-cook them slightly so they’re not raw in the finished dish.
Vegetarian Version: Skip the meat entirely and add an extra cup of vegetables, plus a sprinkle of smoked paprika for depth.

How to Make Easy Make-Ahead Breakfast Casserole

Step 1: Prepare the Base

Grease your baking dish and arrange bread cubes in an even layer at the bottom. This creates the foundation that will soak up all the delicious egg mixture.

Step 2: Cook the Filling

Heat olive oil in a large skillet and add sausage with herbs, breaking it into bite-sized pieces. Add onion, garlic, peppers, mushrooms, and spinach, cooking until vegetables have softened and sausage is mostly cooked through.

Step 3: Layer the Ingredients

Spread the sausage and vegetable mixture evenly over the bread layer. This ensures every bite has a perfect balance of flavors.

Step 4: Add the Egg Mixture

Whisk together eggs, salt, pepper, milk, and shredded cheese until well combined. Pour this mixture evenly over the sausage and vegetables, making sure to cover everything.

Step 5: Rest and Refrigerate

Cover the casserole and refrigerate for at least 30 minutes or overnight. This resting period is crucial as it allows the bread to absorb the egg mixture, resulting in a better texture.

Step 6: Bake to Perfection

Bake uncovered at 375°F until golden on top and set in the center, about 40-45 minutes. Let it cool slightly before serving to allow the casserole to set properly.

Pro Tips for Making the Recipe

Bread Choice Matters: The drier your bread, the better it will absorb the egg mixture without becoming soggy. If your bread is fresh, toast the cubes briefly in the oven before using.
Don’t Skip the Rest: Allowing the casserole to rest before baking isn’t just for convenience – it’s essential for texture as the bread needs time to soak up the egg mixture.
Vegetable Prep: Don’t overcook your vegetables in the skillet – they’ll continue cooking in the oven. Aim for slightly firm vegetables in the pre-cooking stage.
Even Distribution: When pouring the egg mixture, make sure it gets into all corners of the dish. A gentle shake of the pan helps distribute it evenly.
Checking Doneness: The casserole is ready when the center is set but still has a slight jiggle. A toothpick inserted in the center should come out clean.

How to Serve

This versatile breakfast casserole shines in multiple settings:

Garnishes

Top with chopped fresh herbs like parsley or chives, sliced green onions, a dollop of sour cream, or a sprinkle of hot sauce for those who enjoy a kick.

Complete the Meal

Pair with a fresh fruit salad, crispy hash browns, or simple mixed greens dressed with vinaigrette for a complete brunch spread.

Holiday Serving

For special occasions, serve alongside mimosas or a coffee bar with various creamers and syrups for a festive brunch experience.

Make Ahead and Storage

Make Ahead

This recipe is designed for planning ahead! Assemble the entire casserole up to 24 hours before baking, cover, and refrigerate. When ready to bake, let it sit at room temperature for 10-15 minutes as your oven preheats.

Storing Leftovers

Store leftover casserole in an airtight container in the refrigerator for up to 5 days. Individual portions make excellent grab-and-go breakfasts throughout the week.

Freezing

You can freeze this casserole either before or after baking. To freeze unbaked casserole, assemble, cover with plastic wrap and then aluminum foil, and freeze for up to 3 months. Thaw overnight in the refrigerator before baking. For baked casserole, cool completely, cover well, and freeze for up to 3 months.

Reheating

Microwave individual portions for quick reheating, or warm larger portions covered with foil in a 325°F oven until heated through (about 20 minutes). Remove the foil for the last 5 minutes to crisp up the top again.

FAQs

Can I make this casserole without the bread layer?

Absolutely! The bread adds nice texture and helps absorb moisture, but you can omit it for a more frittata-like dish. Alternatively, substitute frozen hash browns (about 3 cups) for a gluten-free option with a different but equally delicious texture.
Why is my breakfast casserole watery?

This typically happens when vegetables release too much moisture during baking. Make sure to pre-cook vegetables thoroughly and drain any excess liquid before adding them to the casserole. Also, using stale or toasted bread helps absorb moisture better than fresh bread.
Can I use egg whites or an egg substitute instead of whole eggs?

Yes, though the texture and richness will be different. For a lower-cholesterol version, substitute half the eggs with egg whites (2 whites = 1 whole egg). Commercial egg substitutes also work following package conversion guidelines, but expect a lighter final dish.
How do I know when the casserole is fully cooked?

The casserole should be golden brown on top with crispy edges. The center should be set but might have a slight jiggle – similar to a cheesecake. A toothpick inserted in the center should come out clean without wet egg mixture. If the top browns too quickly before the center is done, cover loosely with foil for the remaining bake time.

Final Thoughts

This Make-Ahead Breakfast Casserole has become my go-to solution for both special occasion brunches and busy weekday mornings. There’s something incredibly satisfying about waking up knowing breakfast is practically ready to go – just pop it in the oven while you enjoy your coffee! With endless customization options, this versatile recipe can be adapted to suit any taste preference or dietary need. Whether you’re feeding a crowd or meal prepping for yourself, give this comforting, flavor-packed casserole a try – your future self will thank you!

Easy Make-Ahead Breakfast Casserole Recipe

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Author: Lisa
Prep Time: 20 minutes
Cook Time: 45 minutes
Total Time: 1 hour 30 minutes
Yield: Serves 12 1x
Category: Breakfast
Method: Baking
Cuisine: American

Print Recipe

Description

This Easy Make-Ahead Breakfast Casserole is a hearty and customizable dish perfect for feeding a crowd or meal prepping for the week. Packed with crusty bread, flavorful sausage, vibrant vegetables, and melty cheese, it’s the ultimate comfort breakfast. The best part? You can assemble everything the day before, making mornings stress-free while still enjoying a warm, home-cooked meal. Serve this versatile dish plain or pair it with your favorite sides for a complete start to your day.

Instructions

Prepare the Baking Dish
Grease a 9×13-inch or any 3–4-quart oven-safe dish. Evenly layer the bread cubes across the bottom of the pan as the casserole’s base.
Cook the Sausage and Vegetables
Heat olive oil in a large skillet over medium heat. Add the ground sausage and optional rosemary or Italian seasoning. Break the sausage into bite-size pieces using a wooden spoon or spatula as it cooks. Add the onion, garlic, bell peppers, mushrooms, and spinach to the skillet, and cook until the vegetables are slightly softened and the sausage is mostly cooked through—about 5–6 minutes. Remove the skillet from heat and spread the mixture evenly over the bread cubes in the baking dish.
Whisk the Egg Mixture
In a mixing bowl, whisk together the eggs, salt, pepper, milk or half-and-half, and shredded cheddar cheese. Pour this mixture evenly over the sausage and vegetable layer in the baking dish. Sprinkle a bit more salt and pepper on top, if desired.
Refrigerate the Casserole
Cover the casserole with plastic wrap or aluminum foil and refrigerate for at least 30 minutes or up to 24 hours for maximum convenience. When ready to bake, allow the casserole to sit at room temperature for 10–15 minutes while preheating the oven.
Bake the Casserole
Preheat the oven to 375°F (191°C). Bake the uncovered casserole until the top is golden, the edges are crisp, and a toothpick inserted into the center comes out clean—approximately 40–45 minutes.
Cool, Serve, and Enjoy
Let the baked casserole cool for about 10 minutes before slicing and serving. Garnish with green onions and parsley for added flavor and color.
Storing Leftovers
Leftovers can be stored in the refrigerator for up to 5 days. Reheat individual portions in the microwave.

Notes

Make-Ahead: You can prepare and assemble the casserole up to 24 hours in advance. For best results, cover and refrigerate until ready to bake.
Freezing: The casserole can be frozen pre-baked or post-baked for up to 3 months. If freezing after assembly, cover with plastic wrap and foil before freezing. Thaw overnight in the fridge and bake as directed. For freezing after baking, allow it to cool completely, then wrap and freeze. Thaw overnight and reheat in a 350°F (177°C) oven for 25–30 minutes.
Bread Tips: Use crusty bread such as sourdough or French bread. If bread is fresh, toast it in a 300°F (149°C) oven for 10 minutes to firm it up before using.
Substitutions: Sausage can be replaced with turkey, beef, chicken, bacon, or ham. Vegetables like broccoli, zucchini, or kale can be added or substituted based on preference.
Vegetarian Option: Omit the meat and substitute with an additional cup of vegetables.
Dairy-Free: Use a dairy-free milk alternative and skip or replace cheese with a dairy-free option.