Overnight Croissant Breakfast Bake

This overnight croissant breakfast casserole transforms buttery croissants into a savory morning masterpiece that can be prepared the night before. Perfect for holiday mornings or weekend brunches when you want something special without the early morning rush.

I first made this for Christmas morning three years ago, and it has become our non-negotiable holiday tradition. My mother-in-law even requested the recipe after claiming she would "never make a breakfast casserole."

Ingredients

• Butter croissants: the foundation of this dish, providing flaky, buttery layers that absorb the egg mixture beautifully
• Breakfast sausage: adds hearty flavor and protein to keep everyone satisfied until lunch
• Cheddar cheese: creates gooey pockets of deliciousness throughout the casserole
• Eggs and dairy: the custard mixture that binds everything together while keeping it moist
• Aromatic seasonings: dry mustard, paprika, and garlic powder create depth without overwhelming
• Butter and flour: essential for making the velvety gravy that takes this casserole to the next level

Step-by-Step Instructions

Sauté the Aromatics:

Heat olive oil in a skillet over medium heat until it shimmers, then add chopped onions. Cook for 5-7 minutes, stirring occasionally until they become soft and translucent. The onions should start to smell sweet as they cook.

Brown the Sausage:

Add breakfast sausage to the softened onions, breaking it apart with a wooden spoon. Cook for 8-10 minutes until no pink remains and the sausage is browned and crumbly. Drain the fat but reserve about 2 tablespoons for the gravy.

Assemble the Base:

Tear croissants into bite-sized chunks about 2 inches across. In a large bowl, gently toss the torn croissants with the cooled sausage mixture and shredded cheddar. Transfer this mixture to a well-greased 9×13-inch baking dish, ensuring even distribution.

Prepare the Egg Mixture:

In a separate bowl, vigorously whisk eggs until frothy, then add heavy cream, half cup of milk, dry mustard, salt, pepper, paprika, and garlic powder. Whisk until completely combined and smooth. Pour this custard evenly over the croissant mixture, pressing gently to ensure absorption.

Refrigerate Overnight:

Cover the baking dish tightly with plastic wrap or aluminum foil and refrigerate for at least 8 hours or overnight. This resting period allows the croissants to soak up the egg mixture completely.

Bake to Golden Perfection:

Preheat oven to 350°F. Remove casserole from refrigerator while oven heats. Bake uncovered for 35-45 minutes until the top is golden brown and the center is set but still slightly jiggly. A knife inserted in the center should come out mostly clean.

Make the Gravy:

In a saucepan over medium heat, melt butter with reserved sausage fat. Sprinkle flour over the fat and whisk constantly for 60-90 seconds until it forms a smooth paste and smells slightly nutty. Gradually pour in remaining milk, whisking continuously to prevent lumps. Cook for 3-5 minutes until thickened to coat the back of a spoon. Season with salt and pepper.

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My secret ingredient is the dry mustard powder. My grandmother always added it to her egg dishes, and it brings a subtle tanginess that balances the richness of the croissants. When my children smell this baking, they come running to the kitchen without having to be called for breakfast.

Making Ahead and Storage

This casserole was designed for make-ahead convenience. You can prepare everything up to the point of baking and refrigerate for up to 24 hours. For longer storage, you can freeze the unbaked casserole for up to 2 months. Thaw completely in the refrigerator overnight before baking. Leftover baked casserole keeps well in the refrigerator for up to 3 days. Reheat individual portions in the microwave for 1-2 minutes or the entire casserole covered with foil in a 325°F oven until heated through.

Perfect Substitutions

This recipe welcomes adaptation based on what you have available. Instead of breakfast sausage, try diced ham, crumbled bacon, or for a vegetarian version, sautéed mushrooms and spinach. The cheddar cheese can be swapped for Gruyère, fontina, or pepper jack for a spicier kick. If croissants aren't available, brioche, challah, or even a good quality French bread will work. Just ensure the bread is slightly stale to better absorb the egg mixture.

Serving Suggestions

While delicious on its own, this casserole becomes a complete brunch when paired with a simple green salad dressed with lemon vinaigrette to cut through the richness. For a special occasion brunch, serve alongside a fruit platter, yogurt parfaits, and mimosas or Bloody Marys. The gravy can be served on the side, allowing guests to add as much or as little as they prefer, or drizzled over individual portions just before serving.

Frequently Asked Questions

→ Can I use pre-cooked sausage for this dish?

Yes, you can use pre-cooked sausage. Simply crumble it and add it directly to the croissant mixture.

→ Can I make this dish vegetarian?

Absolutely! Substitute the sausage with sautéed mushrooms or your favorite plant-based sausage alternative.

→ How should I store leftovers?

Store leftovers in an airtight container in the refrigerator for up to three days. Reheat in the oven or microwave before serving.

→ What other cheeses can I use?

You can try mozzarella, gouda, or even a spicy pepper jack for a different flavor.

→ Can I use a different type of bread instead of croissants?

Yes, brioche or challah bread are great substitutes that will also soak up the egg mixture beautifully.