Overnight Breakfast Casserole

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This Overnight Breakfast Casserole makes holiday mornings so much easier! Made with soft, buttery brioche bread, it’s rich, delicious, and perfect for feeding a crowd. You can prep everything the night before, then bake it fresh in the morning while everyone gets ready. Serve it with my Homemade Cinnamon Rolls and Crockpot Hot Chocolate for a holiday breakfast everyone will love.

 

Ingredient Notes

Most of these ingredients are kitchen staples, and each one adds something good to this breakfast casserole. Here’s what you’ll need:

• Brioche bread or buns: Brioche adds a buttery sweetness, but regular buns work, too.
• Ground breakfast sausage: Use your favorite breakfast sausage for a savory base.
• Onion: Finely diced onion adds flavor and a touch of sweetness.
• Eggs: Bind the ingredients together and give the casserole its fluffy texture.
• Half-and-half: Adds richness and keeps the egg mixture tender as it bakes.
• Sharp cheddar cheese: Brings a bold, cheesy flavor that pairs well with the sausage.
• Dry mustard: Adds a subtle tang that balances the cheese’s richness.
• Onion powder: Boosts the savory flavor without adding extra texture.
• Salt & pepper: Season to taste, keeping in mind that the sausage and cheddar already contain salt.

How to Make Overnight Breakfast Casserole

Overnight Breakfast Casserole takes a little prep the day before, but the morning work is easy. Follow these steps to get everything ready for the fridge, then bake it the next morning. The printable recipe card below has the full ingredients and measurements.

2 Days Before Baking

Step 1: Cube and Dry the Bread

Cut 6 cups of brioche bread or buns into cubes and spread them on a large baking sheet. Leave them out overnight to dry.

If you need to skip this step, it is NOT a deal breaker. You can totally use fresh bread, and it will turn out just fine if you don’t have time or forgot to plan that far ahead. The drier the bread, the more texture the finished casserole will have. Fresh bread will make it a bit softer (but not quite soggy, thanks to the eggs), so don’t worry, and do NOT let that stop you from making this casserole.

The Night Before

Step 2: Brown the Sausage and Onion

Cook the diced onion and breakfast sausage in a skillet over medium-high heat until the sausage is browned with a few crispy bits and the onion is soft and golden. Break the sausage into small pieces as it cooks.  I love using this meat-chopping tool at the end of cooking to get really small pieces.

Feel free to add any vegetables or other meat you’d like (mushrooms, spinach, bell peppers, ham, bacon, etc.) to your breakfast bake. Serve with some hot sauce for a spicy kick!

Step 3: Prepare the Baking Dish

Grease a 9×13-inch baking dish with butter or nonstick spray. Spread the dried bread cubes in the dish, then sprinkle with 1 cup of shredded cheddar cheese.

Step 4: Add the Sausage Mixture

Spread the cooked sausage and onion evenly over the bread and cheese.

Step 5: Mix and Pour the Egg Mixture

In a bowl, whisk together the eggs, half-and-half, dry mustard, onion powder, salt, and black pepper. Pour the mixture evenly over the bread and sausage, then sprinkle the remaining 1 cup of cheddar cheese on top.

Step 6: Refrigerate Overnight

Cover the dish with plastic wrap and refrigerate overnight so the bread has time to soak up the egg mixture.

The Next Morning

Step 7: Preheat the Oven

Preheat the oven as directed in the recipe card. Remove the casserole from the refrigerator and let it sit at room temperature for 30–40 minutes before baking.

Step 8: Bake

Remove the plastic wrap and bake for about 1 hour, or until the eggs are puffed and set and the top is golden brown. Serve hot.

Tips for Success

• Drain any excess grease: If your sausage releases a lot of grease, drain off the excess before adding it to the casserole so the bottom doesn’t turn oily.
• Shred your own cheese: Freshly shredded cheddar melts nicely and gives you that gooey, cheesy topping.
• Cover the whole dish: Pour the egg mixture evenly over the dish, making sure the corners get some, too.
• Check the center: The top might look done before the eggs are fully cooked. Check the middle to make sure it’s set before serving.
• Let it rest before slicing: Let the casserole rest for 5–10 minutes after baking. This helps the slices hold together when you serve them.

What to Serve With Breakfast Casserole

Serve this breakfast casserole with fresh fruit, something sweet, or a simple breakfast side to round out the meal.

• Cinnamon Rolls: Soft, sweet cinnamon rolls balance the savory sausage and cheddar.
• Belgian Waffles: Crispy waffles add a sweet touch to your breakfast spread.
• Ambrosia Salad: This creamy fruit salad adds a sweet, fruity side to your holiday breakfast spread.
• Hot Chocolate: A warm, chocolatey drink that’s perfect for a weekend breakfast.
• Banana Bread: Sweet banana bread pairs well with the savory eggs, sausage, and cheese.

Save this best breakfast casserole recipe to refer back to later by printing, bookmarking, or sharing! It’s perfect for Christmas breakfast or other special occasions. Have a great week, friends! 🙂

Variations

Want to switch things up? Here are a few easy ways to change this casserole.

• Try different bread: French bread or sourdough works just as well as brioche or buns.
• Change the meat: Try cooked bacon, diced ham, or turkey sausage instead of breakfast sausage.
• Add veggies: Toss in sautéed bell peppers, mushrooms, or spinach.
• Switch the cheese: Monterey Jack or Colby Jack works well here, too.

More Hearty Breakfast Recipes!

• Southwest Egg and Tater Tot Casserole
• Crockpot Smoked Sausage & Hashbrown Casserole
• Perfect French Toast Casserole
• Breakfast Tacos
• Breakfast Burritos

Storing and Reheating

To Store: Cover leftovers or transfer them to an airtight container and refrigerate for up to 4 days. The flavors are even better the next day!

To Reheat: Microwave individual portions for 30 seconds to 1 minute, or until heated through.

Freezing Instructions

To Freeze: Let the baked casserole cool completely, then cover tightly with aluminum foil and place in a freezer-safe bag or container. Freeze for up to 2 months.

To Reheat: Thaw overnight in the refrigerator, then bake at 350°F for about 20 minutes, or until heated through.

If you make this recipe, I would really appreciate it if you would give it a star rating and leave your review in the comments! If you have a picture of your finished dish, post it on Instagram using the hashtag #laurenslatest and tag me @laurens_latest.