Easy Brunch Casserole Recipe | Make-Ahead Breakfast

An easy brunch casserole is one of those recipes that makes hosting breakfast feel effortless. Everything comes together in one baking dish with fluffy eggs, savory sausage, melted cheese, fresh vegetables, and tender bread.

It’s especially perfect for weekend brunches, holiday mornings, family gatherings, Mother’s Day breakfast, or any morning when you want a warm homemade meal without spending hours in the kitchen.

The best part? You can assemble this casserole the night before and simply bake it in the morning.

Why You’ll Love This Easy Brunch Casserole

Easy to prepare
Perfect for make-ahead breakfasts
Great for weekend brunch
Feeds a family or small gathering
Uses simple ingredients
Everything bakes in one dish
Easy to customize
Delicious served warm or at room temperature

Ingredients

For the Casserole

10 large eggs
1 1/2 cups whole milk
1 cup shredded cheddar cheese
1/2 cup shredded Monterey Jack cheese
1 pound breakfast sausage
6 cups cubed French bread or brioche
1/2 medium yellow onion, diced
1 red bell pepper, diced
2 cups fresh baby spinach
1 teaspoon Dijon mustard
1/2 teaspoon garlic powder
1/2 teaspoon salt
1/4 teaspoon black pepper
1/2 teaspoon Italian seasoning
2 tablespoons chopped fresh parsley

For the Baking Dish

1 tablespoon butter or cooking spray

How to Make Easy Brunch Casserole

1. Prepare the Baking Dish

Preheat your oven to 350°F.

Lightly grease a 9×13-inch baking dish with butter or cooking spray.

This helps prevent the casserole from sticking and makes serving easier.

2. Cook the Breakfast Sausage

Heat a large skillet over medium heat.

Add the breakfast sausage and cook, breaking it apart with a wooden spoon as it browns.

Continue cooking until the sausage is completely cooked through.

Transfer it to a plate lined with paper towels to remove excess grease.

3. Cook the Vegetables

Using the same skillet, add the diced onion and bell pepper.

Cook for approximately 3 to 4 minutes until they begin to soften.

Add the spinach and cook for another minute or two, just until it wilts.

Remove the skillet from the heat.

4. Prepare the Egg Mixture

In a large mixing bowl, whisk together the eggs, milk, Dijon mustard, garlic powder, salt, black pepper, and Italian seasoning.

Whisk until the mixture is smooth and evenly combined.

5. Layer the Bread

Spread the cubed bread evenly across the bottom of the prepared baking dish.

You want the bread distributed fairly evenly so every serving gets a good combination of ingredients.

6. Add the Sausage and Vegetables

Scatter the cooked sausage over the bread.

Add the sautéed onion, bell pepper, and spinach.

Spread everything evenly across the casserole.

7. Add the Cheese

Sprinkle the cheddar and Monterey Jack cheese over the top.

You can reserve a little cheese for the final layer if you want an especially golden cheesy crust.

8. Pour Over the Egg Mixture

Slowly pour the egg mixture evenly over the entire casserole.

Gently press down on the bread with a spatula so it absorbs some of the egg mixture.

Don’t completely flatten the bread.

9. Rest the Casserole

For the best texture, allow the assembled casserole to sit for about 15 to 20 minutes before baking.

You can also cover it tightly and refrigerate it overnight for a make-ahead brunch.

10. Bake

Place the casserole in the preheated oven.

Bake uncovered for approximately 40 to 50 minutes.

The top should be golden and the center should be set.

If the top starts browning too quickly, loosely cover the casserole with aluminum foil for the remaining baking time.

11. Rest Before Serving

Remove the casserole from the oven and allow it to rest for approximately 10 minutes.

Sprinkle fresh parsley over the top.

Slice into squares and serve warm.

Can I Make This Brunch Casserole the Night Before?

Absolutely.

That’s one of the reasons I love this recipe for entertaining.

Prepare the entire casserole, cover the baking dish tightly with plastic wrap or aluminum foil, and refrigerate overnight.

In the morning, remove it from the refrigerator while the oven preheats.

Bake as directed, adding a few extra minutes if necessary because the casserole starts cold.

For the freshest texture, don’t add the final fresh parsley until after baking.

What Is the Best Bread to Use?

Several types of bread work well.

French Bread

A classic option that absorbs the egg mixture nicely.

Brioche

Creates a softer, richer and slightly sweeter casserole.

Sourdough

Adds a subtle tang and hearty texture.

Challah

Excellent for a rich brunch casserole.

Day-Old Bread

Slightly stale bread is actually ideal because it absorbs the egg mixture without becoming too mushy.

Easy Brunch Casserole Variations

One of my favorite things about this recipe is how easy it is to change.

Bacon Brunch Casserole

Replace the sausage with cooked crispy bacon.

Ham and Cheese Casserole

Use diced cooked ham with cheddar and Swiss cheese.

Vegetarian Brunch Casserole

Skip the sausage and add extra spinach, mushrooms, bell peppers, tomatoes, and onions.

Mushroom Brunch Casserole

Sauté sliced mushrooms with the onions before adding them to the casserole.

Spicy Brunch Casserole

Add diced jalapeños and use pepper Jack cheese.

Mexican-Inspired Brunch Casserole

Add cooked chorizo, Monterey Jack cheese, bell peppers, and a little cumin.

Serve with salsa and avocado.

Can I Add Potatoes?

Yes.

Cooked diced potatoes or frozen hash browns work particularly well.

If using frozen hash browns, make sure they are thawed and excess moisture is removed before adding them.

You can layer them underneath the bread or use them instead of the bread.

What Cheese Is Best?

Cheddar is my go-to because it melts beautifully and adds plenty of flavor.

You can also use:

Monterey Jack
Pepper Jack
Swiss
Gruyère
Colby Jack
Mozzarella

A combination of two cheeses creates a richer flavor.

What to Serve With Brunch Casserole

This casserole is hearty enough to serve on its own, but a few fresh sides make brunch feel extra special.

Try serving it with:

Fresh strawberries
Blueberries
Mixed berries
Sliced avocado
Fresh fruit salad
Roasted potatoes
Green salad
Toast
Orange juice
Coffee

For a holiday brunch, I love serving it with a big bowl of fresh fruit and warm coffee.

How Do I Know When It’s Done?

The center should be set and shouldn’t look liquid or wet.

Insert a knife into the center of the casserole.

It should come out mostly clean.

If you’re using a food thermometer, the egg mixture should reach 160°F in the center.

Avoid overbaking because the eggs can become dry and rubbery.

Tips for the Best Easy Brunch Casserole

Use day-old bread. It absorbs the custard better than very fresh bread.

Don’t add raw sausage. Cook the sausage completely before assembling the casserole.

Don’t overload the vegetables. Too many watery vegetables can make the casserole soggy.

Grate your own cheese when possible. Freshly grated cheese melts more smoothly.

Let it rest after baking. Ten minutes makes slicing much easier.

Don’t overbake. Remove it as soon as the center is set.

How to Store Leftovers

Allow leftovers to cool completely.

Transfer individual portions to airtight containers or cover the baking dish tightly.

Refrigerate for up to 4 days.

How to Reheat

For individual portions, microwave for approximately 60 to 90 seconds, checking and adding more time if needed.

For larger portions, cover with foil and reheat in a 325°F oven until warmed through.

Can I Freeze Brunch Casserole?

Yes.

Allow the cooked casserole to cool completely.

Cut it into individual portions and wrap them tightly.

Place the portions in a freezer-safe container.

Freeze for up to 2 months.

Thaw overnight in the refrigerator before reheating.

The texture may be slightly softer after freezing, but it will still make a convenient breakfast.

Frequently Asked Questions

Can I make this without sausage?

Yes. Simply leave it out and add more vegetables, mushrooms, or another protein such as cooked ham or bacon.

Can I use turkey sausage?

Absolutely. Turkey sausage is an easy way to make the casserole lighter while keeping plenty of flavor.

Can I use frozen spinach?

Yes. Thaw it completely and squeeze out as much excess moisture as possible before adding it.

Can I use gluten-free bread?

Yes. Substitute your favorite gluten-free bread using the same approximate quantity.

Can I make this vegetarian?

Yes. Leave out the sausage and increase the vegetables. Mushrooms, spinach, bell peppers, onions, and tomatoes all work well.

Can I prepare this for a holiday breakfast?

Definitely. This is one of the best reasons to make it. Assemble everything the night before, refrigerate it, and bake it fresh in the morning.

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