Growing up, my mom always made breakfast casseroles for Christmas morning, but they were never quite ready when we wanted to eat. We’d sit there, stomachs growling, waiting what felt like forever while it baked.

That’s why I love this overnight sausage and egg casserole – you do all the prep work the night before, and just pop it in the oven when you wake up. No more hungry kids (or adults) waiting around on Christmas morning.

Plus, it’s basically impossible to mess up, which means less stress during the holidays. My family actually prefers this version to my mom’s original recipe, but I haven’t told her that yet.

Why You’ll Love This Breakfast Casserole

Make-ahead convenience – You can prep this casserole the night before, making your morning routine stress-free. Just pop it in the oven when you wake up!
Basic ingredients – This recipe uses common kitchen staples you probably already have in your fridge and pantry – no fancy ingredients needed.
Perfect for feeding crowds – Whether it’s a holiday breakfast or weekend brunch with friends, this hearty casserole easily feeds a group and can be doubled for larger gatherings.
Customizable recipe – You can swap the sausage for bacon, use different cheeses, or add vegetables to make it your own. It’s hard to go wrong with this flexible recipe.
Filling breakfast – With eggs, sausage, and cheese, this protein-rich casserole will keep everyone satisfied until lunch.

Which Kind of Sausage Should I Use?

For breakfast casseroles, pork breakfast sausage is the most popular choice, and you can go with either mild or hot depending on your heat preference.

Regular bulk breakfast sausage (the kind that comes unformed, rather than in links) works best, since you’ll need to break it up as it cooks.

If you’re looking to cut calories, turkey breakfast sausage makes a good substitute and still provides plenty of flavor. Just make sure to drain any excess grease after cooking, regardless of which type you choose – this helps prevent your casserole from becoming greasy.

A tip from my kitchen: breaking the sausage into small, even pieces while cooking helps it distribute better throughout the casserole.

Ingredient Substitutions

This breakfast casserole is pretty forgiving with substitutions, making it perfect for using what you have on hand.

The bread can be any type you prefer – white, wheat, sourdough, or even leftover hamburger buns will work (just make sure it’s not too fresh so it can soak up the egg mixture).
While breakfast sausage is traditional, you could swap it for cooked bacon, ham, or even plant-based sausage if you’re cooking for vegetarians.
The cheddar cheese can be replaced with any melting cheese you like – Swiss, Monterey Jack, or a Mexican cheese blend would all be tasty.
For the milk, feel free to use whatever you have in the fridge – whole milk, 2%, or even half-and-half will work, though I wouldn’t recommend using non-dairy alternatives as they might affect how well the eggs set up.

How to Know When the Breakfast Casserole is Done

A perfectly cooked breakfast casserole should be set in the middle and slightly puffed up around the edges – if you give the pan a gentle shake, the center shouldn’t jiggle.

To double-check doneness, insert a knife into the center of the casserole; it should come out clean without any raw egg mixture. The top should be light golden brown, and the cheese should be completely melted.

Let it rest for about 10 minutes after baking, which helps it set up and makes it easier to cut into clean squares.

How to Store and Freeze the Casserole

This breakfast casserole is a great option for meal prep and storing leftovers.

Store: Once cooled, store any remaining portions in an airtight container in the fridge for up to 3 days – just reheat individual servings in the microwave when you’re ready to eat.

Make ahead: The best part about this recipe is that it’s designed to be made ahead – assemble everything the night before, cover with plastic wrap, and let it hang out in the fridge overnight before baking in the morning.

Freeze: If you want to plan further ahead, you can freeze the unbaked casserole for up to 2 months – just thaw it in the fridge overnight before baking as directed.

Overnight Sausage and Egg Casserole FAQ

Why does the bread need to be cubed?

Cubing the bread is important because it creates the perfect texture in this breakfast casserole.

When the bread is cut into cubes, it allows the egg mixture to soak evenly into each piece, creating a consistent texture throughout.

I’ve found that roughly 1-inch cubes work best – any smaller and they’ll get too mushy.

Do I need to let the sausage cool before adding it to the casserole?

Yes, it’s important to let the cooked sausage cool for about 10 minutes before adding it to the casserole mixture.

Hot sausage can start cooking the eggs prematurely when mixed together, and it can also melt the cheese too quickly.

I usually cook the sausage first and let it cool while I prep the other ingredients.

Why is ground mustard used instead of regular mustard?

Ground mustard adds a subtle depth of flavor that regular prepared mustard just can’t match.

It blends seamlessly into the egg mixture without adding any unwanted texture or vinegar taste that you might get from regular mustard.

I’ve been using it in my egg dishes for years, and it really makes a difference in the overall flavor.

Preparation Time	15-20 minutes
Cooking Time	45-55 minutes
Total Time	60-75 minutes
Level of Difficulty	Easy

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

Calories: 2000-2200
Protein: 100-120 g
Fat: 140-160 g
Carbohydrates: 150-170 g

Ingredients

6 cubed slices of bread
1 pound cooked and drained sausage
2 cups grated cheddar cheese
8 large eggs
2 cups milk
1 teaspoon ground mustard
1 teaspoon salt
Pepper to taste

Step 1: Prepare the Baking Dish

Start by greasing a 9×13 inch baking dish to prevent sticking.

Spread the bread evenly across the bottom of the dish.

For optimal results, consider using a sturdier bread such as Pepperidge Farms Sourdough loaf.

Step 2: Add the Sausage and Cheese

Once the bread is in place, evenly sprinkle cooked sausage and shredded cheese over the bread.

This layer should cover the bread completely to ensure even distribution of flavors.

Step 3: Mix the Egg Mixture

In a large measuring cup, whisk together the eggs, milk, dry mustard, salt, and pepper until well combined.

This mixture will serve as the binding agent and flavor enhancer for your casserole.

Step 4: Assemble and Chill

Pour the egg mixture evenly over the layered bread, sausage, and cheese in the pan.

Cover the dish tightly and refrigerate overnight.

This allows the bread to absorb the egg mixture, resulting in a more cohesive texture.

Step 5: Bake the Casserole

When you’re ready to bake, preheat your oven to 325 degrees Fahrenheit.

Place the casserole in the oven and bake for 45-55 minutes, depending on your preferred egg texture.

Cover the dish loosely with foil for the first 30 minutes to prevent the top from over-browning, then remove the foil for the remaining baking time.

To gauge doneness, insert a fork or knife into the center—cooking time may vary based on your oven and preferences regarding egg consistency.

Step 6: Serve

Remove the casserole from the oven once fully baked, allowing it to cool slightly before serving.

Enjoy this savory dish warm, perfect for breakfast or brunch gatherings.