A hearty, savory dish that’s perfect for prepping ahead, this Easy Overnight Breakfast Casserole is packed with flavor and convenience. Full of breakfast sausage, eggs, cheese, and bread, it’s an ideal dish for busy mornings when you want something satisfying and wholesome. With the option to add extra veggies, it can be customized to suit your family’s tastes.

Why You’ll Love This Recipe

This Easy Overnight Breakfast Casserole is the ultimate time-saver, allowing you to prepare everything the night before and bake it fresh the next morning. It’s packed with protein from eggs and sausage, and the combination of cheddar cheese and bread makes it irresistibly comforting. The addition of mustard powder adds a subtle tang, and optional veggies like bell peppers, spinach, or mushrooms make it even more flavorful. It’s a customizable, make-ahead meal that’s perfect for busy weekends, family gatherings, or even a simple weekday breakfast.

Ingredients

1 pound breakfast sausage
1/2 onion, chopped
6 eggs
1 1/2 cups milk of choice
1 teaspoon mustard powder
Salt and pepper to taste
4 cups cubed bread
1 cup shredded cheddar cheese
Optional: chopped bell peppers, spinach, mushrooms

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

Directions

In a skillet, cook sausage and onions over medium heat until the sausage is browned and the onions are softened. Drain any excess fat.
In a large bowl, whisk together eggs, milk, mustard powder, salt, and pepper until fully combined.
Grease a 9×13 baking dish and layer the cubed bread, sausage mixture, cheese, and any optional veggies.
Pour the egg mixture evenly over the top of the bread and sausage layers.
Cover and refrigerate overnight to let the bread soak up the egg mixture.
In the morning, preheat the oven to 350°F (175°C).
Bake uncovered for 45-50 minutes, or until the casserole is set in the middle and golden brown on top.
Allow the casserole to cool slightly before slicing and serving.

Servings and timing

Servings: 6 servings
Prep Time: 15 minutes
Cooking Time: 50 minutes
Total Time: 1 hour 5 minutes

Variations

Vegetarian version: Skip the sausage and use plant-based sausage or tofu for a vegetarian alternative. You can also load it up with more veggies like spinach, zucchini, or tomatoes.
Gluten-free: Use gluten-free bread to make this casserole suitable for those avoiding gluten. You can also add gluten-free sausage or more veggies for extra texture.
Cheese options: Swap out cheddar cheese for other cheeses like mozzarella, pepper jack, or Swiss cheese to change up the flavor profile.

Storage/Reheating

Storage: Leftovers can be stored in an airtight container in the refrigerator for up to 3 days.
Reheating: To reheat, simply microwave individual portions for 30-60 seconds or warm in the oven at 350°F (175°C) for about 10-15 minutes.

FAQs

Can I use a different type of sausage?

Yes, you can use any type of breakfast sausage, such as turkey sausage, pork sausage, or plant-based sausage for a healthier or vegetarian option.

Can I make this casserole without mustard powder?

Yes, if you don’t have mustard powder, you can skip it or substitute with a small amount of Dijon mustard or even a pinch of turmeric for color and flavor.

How do I know when the casserole is done?

The casserole should be golden brown on top and firm in the center. You can test it by inserting a toothpick or knife into the middle—it should come out clean.

Can I make this casserole without bread?

If you need a low-carb or gluten-free version, you can substitute bread with cauliflower rice or another low-carb bread substitute, though the texture will change slightly.

Can I freeze this casserole?

Yes, this casserole can be assembled and frozen before baking. Cover it tightly with plastic wrap and aluminum foil, and freeze for up to 1-2 months. When ready to bake, thaw in the refrigerator overnight and bake as directed.

How long can I refrigerate this casserole before baking?

It’s best to refrigerate overnight for at least 8 hours, but you can also refrigerate it for up to 24 hours before baking.

Can I add extra vegetables to this casserole?

Yes, you can add bell peppers, mushrooms, spinach, or any other vegetables of your choice. Just be sure to sauté any vegetables that release moisture to prevent the casserole from becoming soggy.

How can I make this casserole spicier?

If you like some heat, add diced jalapeños or sprinkle in some red pepper flakes when layering the ingredients. You could also use a spicier sausage variety.

Can I use a different type of cheese?

Yes, you can use any cheese you prefer. Some great alternatives include mozzarella, Monterey Jack, or even goat cheese for a tangy twist.

Is this casserole suitable for a crowd?

Yes, this recipe can easily be doubled to serve a larger group. Just be sure to adjust the baking time slightly if using a larger dish.

Conclusion

This Easy Overnight Breakfast Casserole is the perfect solution for busy mornings when you want a hearty, savory breakfast with minimal effort. It’s rich in flavor, packed with protein, and completely customizable. Whether you’re preparing it for a family breakfast, a weekend brunch, or a holiday gathering, it’s sure to be a hit. With its make-ahead convenience, it’s a dish you can rely on for any occasion!

Easy Overnight Breakfast Casserole

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Print Recipe

This Easy Overnight Breakfast Casserole is the ultimate make-ahead dish for busy mornings. Packed with protein from eggs and sausage, and topped with melted cheddar cheese, this savory casserole is perfect for brunch, holidays, or meal prep. Customizable with veggies and different cheeses, it’s a hearty and wholesome start to your day!

Total Time: 1 hour 5 minutes
Yield: 6 servings

Instructions

In a skillet, cook sausage and onions over medium heat until the sausage is browned and the onions are softened. Drain any excess fat.
In a large bowl, whisk together eggs, milk, mustard powder, salt, and pepper.
Grease a 9×13 baking dish and layer the cubed bread, sausage mixture, cheese, and any optional veggies.
Pour the egg mixture evenly over the bread and sausage layers.
Cover and refrigerate overnight to let the bread soak up the egg mixture.
In the morning, preheat oven to 350°F (175°C).
Bake uncovered for 45-50 minutes, or until golden brown on top and set in the center.
Let cool slightly before slicing and serving.

Notes

Vegetarian Version: Skip the sausage and use plant-based sausage or tofu, adding more veggies for texture.
Gluten-Free: Use gluten-free bread and sausage to make this casserole gluten-free.
Cheese Options: Try mozzarella, pepper jack, or Swiss cheese for a different flavor.
Make-Ahead: Prepare the casserole the night before and bake it in the morning for a stress-free breakfast.

Author: Sophia
Prep Time: 15 minutes
Cook Time: 50 minutes
Category: Breakfast, Brunch, Make-Ahead, Family Meals
Method: Baking, Stovetop
Cuisine: American
Diet: Vegetarian