Sausage Breakfast Casserole (Easy Make-Ahead Recipe)

I am a big fan of breakfast casseroles, and this one is my family’s favorite. I make it every year for Christmas morning, plus the occasional weekend brunch, and yes, sometimes even for dinner! It’s hearty, delicious, easy to prepare ahead of time, and endlessly versatile.

Unlike my tater tot breakfast casserole, this recipe uses cubes of day-old bread to soak up a savory mixture of eggs, milk, sausage, onions, Parmesan, and Gouda. I used sourdough for the casserole pictured here, but it’s just as delicious with day-old French bread, challah, or brioche. Once baked, the top is golden and slightly crispy, while the inside stays soft and custardy, almost like a savory bread pudding.

The trick is giving the bread enough time to absorb the eggs and milk before baking. I’ve made this casserole after refrigerating it for just one hour and after letting it chill overnight, and both turn out perfectly. And just like my biscuits and gravy casserole, this sausage breakfast casserole can be assembled the night before and baked the next morning. For the ultimate breakfast spread, I highly recommend serving it with fresh squeezed orange juice and fresh berries or a yummy fruit salad and bakery-style blueberry muffins.

Ingredients and Substitutions

This sausage breakfast casserole is made with simple, easy-to-find ingredients. For the complete list of ingredients and measurements, see the recipe card at the bottom of the post.

• Ground sausage: I highly recommend making this casserole with pork breakfast sausage for its classic, savory flavor, but sweet or hot Italian sausage also works well. Italian sausage will give the casserole a different flavor depending on its seasonings. Ground chicken or turkey sausage is also an option. Whichever you choose, cook the sausage thoroughly before adding it to the egg mixture.
• Onion and olive oil: Yellow onion adds a little sweetness and flavor to the sausage as it browns. White onion or shallots work as substitutes, and you can use butter in place of olive oil.
• Eggs: Eight large eggs form the base of the casserole, helping everything hold together as it bakes. I recommend sticking with whole eggs for the best results.
• Whole milk: Three cups of whole milk combine with the eggs to create the custard that soaks into the bread. Half-and-half can be substituted for a richer casserole, but I prefer whole milk for a balance of richness and texture. My crustless quiche uses a similar egg-and-dairy custard, but without the bread.
• Parmesan and Gouda cheese: Parmesan adds a salty, nutty flavor, while Gouda melts into the casserole, making it extra cheesy and delicious. You can substitute cheddar, Swiss, or pepper jack for the Gouda, depending on your preference. I recommend shredding the cheese yourself for smoother melting.
• Day-old bread: You’ll need 10 cups of cubed, day-old bread, measured after cutting. I used sourdough for the casserole pictured here, but I’ve also made it using French bread, challah, and brioche. The bread should be slightly dry so it can absorb the egg and milk mixture without becoming overly mushy. Tip: If you’re starting with fresh bread, cut it into cubes and dry it in a 300°F oven for 10-15 minutes, then let it cool before assembling the casserole.
• Seasonings: Salt, black pepper, and garlic powder add flavor without overpowering the sausage and cheese. Keep in mind that both the sausage and Parmesan contribute salt, so additional seasoning may not be necessary.
• Fresh parsley: Optional, but a little chopped parsley adds freshness and color just before serving.

How to Make Sausage Breakfast Casserole

1. Brown the sausage and onions. Lightly grease a 9×13-inch baking dish with nonstick cooking spray and set aside. Heat the olive oil in a large skillet over medium heat. Add the diced onion and cook for 3-4 minutes, until it starts to soften. Add the ground sausage and continue cooking for approximately 12-15 minutes, breaking it into smaller pieces as it browns. Once the sausage is fully cooked and the onions are soft, remove from the heat and allow to cool slightly. Tip: To speed up cooling, transfer the sausage and onion mixture to a shallow dish and place it in the refrigerator or freezer for a few minutes, stirring occasionally, until it’s no longer hot. Spreading it out helps it cool faster than leaving it in the skillet.

2. Whisk together the eggs and milk. In a large mixing bowl, whisk together the eggs, whole milk, salt, black pepper, and garlic powder until well combined. This mixture forms the custard that will soak into the bread and hold the casserole together as it bakes.

3. Add the sausage and cheese. Once the sausage has cooled, stir the grated Parmesan, shredded Gouda, and slightly cooled sausage and onions into the egg mixture. Mix until everything is evenly combined.

4. Add the bread to the baking dish. Spread the cubed, day-old bread evenly in the prepared baking dish. You want the bread distributed throughout the dish so that every serving has a good balance of bread, sausage, eggs, and cheese.

5. Pour the egg mixture over the bread. Slowly pour the sausage, cheese, and egg mixture over the bread, distributing the sausage and cheese as evenly as possible. Pour any remaining liquid from the bowl over the top, then use the back of a large spoon to gently press the bread into the mixture. This helps moisten the bread and ensures that the pieces on top don’t stay dry.

6. Cover and refrigerate. Cover the baking dish tightly with aluminum foil and refrigerate for at least 1 hour or overnight. Don’t skip this step! The bread needs time to absorb the eggs and milk, which is what gives the finished casserole its soft, custardy texture.

7. Bake the breakfast casserole. When you’re ready to bake, preheat the oven to 350°F. Place the covered casserole in the oven and bake for 35 minutes. Remove the foil and continue baking for approximately 25 minutes, or until the top is golden brown and the center is set. If refrigerated overnight: I’ve found that a thoroughly chilled casserole typically needs an additional 20-30 minutes in the oven. Keep an eye on the top and loosely cover with foil if it starts browning too quickly. The casserole is ready when the center reaches an internal temperature of 165°F.

8. Rest, garnish, and serve. Remove the casserole from the oven and allow it to rest for 5-10 minutes before slicing. This gives the custard a little time to settle, making it easier to cut into neat portions. Garnish with freshly chopped parsley, if desired, and serve warm.

How to Make Sausage Breakfast Casserole Ahead of Time

This sausage breakfast casserole is a great recipe to make ahead of time, especially around the holidays. Assemble everything the night before, cover tightly with aluminum foil, and refrigerate overnight. The next morning, all that’s left to do is bake!

Baking after overnight refrigeration: Preheat the oven to 350°F and bake as directed, keeping in mind that a thoroughly chilled casserole typically needs an additional 20-30 minutes in the oven. If the top starts browning too quickly, loosely cover it with foil. The casserole is done when the center is set and reaches an internal temperature of 165°F as measured with an instant-read thermometer.

A note about baking dishes: For overnight preparation, I recommend using a roomy 9×13-inch baking dish that can safely go directly from the refrigerator into a preheated oven. Three good options are the All-Clad Stainless Steel Baking Pan, the Staub stoneware baker, and the Pyrex Deep glass baking dish. The deeper Staub and Pyrex dishes are especially helpful for accommodating the generous amount of bread, sausage, and egg mixture. If using Pyrex, make sure the oven is fully preheated before adding the refrigerated dish, and remove any plastic storage lid before baking. Since glass and ceramic bakeware can have different guidelines for temperature changes, always check the manufacturer’s instructions for your specific dish.

5 Tips for the Best Sausage Breakfast Casserole

1. Start with day-old bread. Fresh, soft bread can become overly mushy as it absorbs the egg and milk mixture. Slightly stale sourdough, French bread, or another sturdy bread works best because it absorbs the custard while maintaining some structure.
2. Drain excess sausage grease. A little fat adds flavor, but too much can make the casserole greasy. If there’s a lot of rendered fat in the skillet after browning the sausage, spoon off the excess before adding it to the egg mixture. Also remember to let the sausage cool slightly so it doesn’t start cooking the eggs prematurely.
3. Make sure the bread is evenly soaked. After pouring the egg mixture into the baking dish, gently press down on any pieces of bread sticking up from the liquid. This helps prevent dry patches and ensures a more consistent texture throughout the dish.
4. Don’t judge doneness by the golden top alone. The bread and cheese may look perfectly browned before the eggs in the center are fully cooked. Check the middle of the casserole with an instant-read thermometer. It should reach 165°F. If the top is browning too quickly, loosely cover it with aluminum foil while the center finishes cooking.
5. Let it rest before slicing. I know it’s tempting to dig right in, but giving the casserole 5-10 minutes to rest after baking allows everything to settle and makes it much easier to cut into neat portions without falling apart.

Easy Breakfast Casserole Variations

One of the things I love about this sausage breakfast casserole is how easy it is to customize. The bread, eggs, and milk form the base, but you can experiment with different meats, cheeses, and vegetables depending on what you have on hand.

Here are a few combinations to try:

• Spinach and mushroom: Add sautéed mushrooms and chopped spinach for extra vegetables and flavor. Cook the mushrooms until they’ve released most of their moisture, and wilt and drain the spinach before adding it to the egg mixture.
• Spicy sausage breakfast casserole: Use hot breakfast sausage, replace the Gouda with pepper jack cheese, and add diced jalapeños or green chiles. Serve with your favorite salsa or hot sauce.
• Bacon, cheddar, and bell pepper: Swap the Gouda for sharp cheddar and add diced red or green bell peppers. Cook the peppers with the onions until softened before adding the sausage. For an extra smoky flavor, sprinkle crispy, crumbled oven-baked bacon over the finished casserole just before serving.
• Italian-inspired: Use sweet or hot Italian sausage, substitute mozzarella for the Gouda, and add sautéed spinach. Keep the Parmesan for its salty, nutty flavor.

Tip: Be careful not to overload the casserole with additional ingredients, especially vegetables that release a lot of water. As a starting point, keep extra vegetables to about 1 cup total, cook off excess moisture, and drain well before adding them. Too much additional moisture can leave the center watery or prevent the casserole from setting properly. And regardless of the variation, keep the original bread, egg, and milk quantities the same and refrigerate for at least one hour before baking.

How to Store, Freeze, and Reheat

• Refrigerator: Transfer leftovers to an airtight container and store in the refrigerator for up to 3-4 days. I recommend cutting the casserole into individual portions before storing so you can easily reheat only what you need.
• Freezer: Yes, you can freeze this sausage breakfast casserole! I recommend freezing it after baking rather than freezing the assembled, unbaked casserole. Divide into individual portions, then wrap tightly in plastic wrap followed by aluminum foil, or place in freezer-safe containers. Freeze for up to 2-3 months. Thaw overnight in the refrigerator before reheating.
• Reheating in the oven: Preheat your oven to 350°F. Place the refrigerated casserole portions in an oven-safe dish and cover loosely with aluminum foil to prevent them from drying out. Heat for approximately 15-25 minutes, depending on the size of the portions, or until warmed through to an internal temperature of 165°F. Remove the foil for the last few minutes if you want to crisp up the top.
• Reheating in the microwave: Place an individual serving on a microwave-safe plate and cover loosely with a microwave-safe lid. Microwave for 1 minute, then continue heating in 30-second intervals until the center reaches 165°F.

Sausage Breakfast Casserole FAQs

More Breakfast Recipes

Croissant Breakfast Sandwich (Freezer-Friendly!)

Crustless Quiche Recipe

Acai Bowl Recipe – How to Make Your Own Acai Bowl

Creamy Baked Eggs with Spinach and Prosciutto