Overnight Croissant Breakfast Casserole Recipe

The Overnight Croissant Breakfast Casserole is the kind of dish that makes breakfast feel like an absolute celebration. Buttery croissants soak up a rich custard, layer up with savory sausage and onions, and turn golden under cheddar cheese. All this magic happens while you sleep, making it perfect for holiday mornings, family brunches, or any day you want to wrap your loved ones in warmth and comfort—with almost no morning fuss! Every forkful is fluffy, cheesy, and loaded with flavor, making this casserole an instant favorite for both casual weekends and special gatherings.

Ingredients You’ll Need

The best part about this irresistible breakfast is how simple but crucial each ingredient is. Every component builds on the last, creating a harmony of textures, flavors, and a pop of color in every bite. Here’s what you’ll want to gather before you start:

• Olive oil: Just a splash helps the onions become soft and sweet without burning during the sauté.
• Onion: Adds an aromatic depth and slight sweetness, making every bite more savory and flavorful.
• Breakfast sausage: Choose mild for a crowd-pleaser, or swap for spicy if your family loves a kick; sausage brings the heartiness.
• Butter croissants: Day-old or fresh, they soak up the custard for pillowy, golden goodness—tear into chunks for best texture!
• Shredded cheddar cheese: Gives your casserole plenty of melt and tangy edge, with gorgeous color on top.
• Large eggs: The backbone of your custard, binding everything together for a fluffy, tender bite.
• Heavy whipping cream: Brings rich creaminess you’ll really taste in the finished casserole.
• Whole milk: Provides body and keeps the casserole light—using part of it for a homemade, silky sausage gravy that’s impossible to skip.
• Dry mustard powder: Delivers a subtle heat and complexity—your secret spice for a breakfast casserole with zing.
• Salt: Heightens all the savory flavors, and adjusts the seasoning perfectly for both casserole and gravy.
• Black pepper: Adds warmth and just the right bite in both the main dish and the gravy side.
• Paprika: A touch of smoky-sweet color and depth throughout the custard mixture.
• Garlic powder: For an extra layer of aroma that rounds everything out without overpowering.
• Butter: Melts to start the creamy, luxurious base for your classic breakfast gravy.
• All-purpose flour: Just enough to thicken your gravy to perfect spooning consistency.

How to Make Overnight Croissant Breakfast Casserole

Step 1: Sauté the Savory Essentials

Heat the olive oil in a large skillet over medium heat, then add your chopped onion. Sauté until the onion turns soft and translucent, which really brings out its sweetness. Add the breakfast sausage, breaking it up with a spatula, and cook until it’s no longer pink and nicely browned. Don’t forget to drain the fat, but keep a few tablespoons for your from-scratch gravy later. Let the sausage mixture cool for a few minutes—it helps keep the custard from scrambling in the next step.

Step 2: Build the Buttery Base

Tear your croissants into large bite-sized pieces—this is a fun job if kids want to help! In a big mixing bowl, toss together the croissant pieces, cooled sausage and onion mix, and shredded cheddar cheese. Stir until everything looks happily combined, then spread the mixture evenly into a greased 9×13-inch baking dish. This forms the flavorful, pillowy base of the Overnight Croissant Breakfast Casserole.

Step 3: Whisk Up the Custard

In a separate bowl, whisk together the eggs, heavy cream, half a cup of the milk, dry mustard powder, salt, pepper, paprika, and garlic powder. Whisk until the spices are evenly distributed and the mixture is totally smooth. Pour this rich custard evenly over the croissant-sausage mixture in your baking pan, making sure it soaks right into the croissants. Cover the pan tightly with plastic wrap or a lid and refrigerate overnight to let the flavors meld and the croissants absorb all that custardy goodness.

Step 4: Bake to Perfection

On the day you plan to serve, preheat your oven to 350°F (175°C). Take off the covering and slide your casserole dish into the oven. Bake for 35 to 45 minutes, keeping an eye out for that moment when the top turns golden and slightly crisp, but the center jiggles just a little when you shake the pan. This means it’s set and cooked through, but still moist and tender inside.

Step 5: Whip Up Creamy Gravy

While the casserole bakes, grab that reserved sausage fat (or use all butter, if you prefer) and melt it together with butter in a saucepan over medium heat. Whisk in the flour, stirring constantly, and cook for a full minute to lose the raw flour taste. Gradually pour in the remaining 2 ½ cups of milk, whisking all the while until the mixture thickens into a smooth, luxurious gravy. Season generously with salt and pepper to taste.

Step 6: Serve and Savor

When the Overnight Croissant Breakfast Casserole is beautifully puffed and golden, let it cool for a few minutes, then spoon generous portions onto plates. Don’t forget a ladleful of warm, creamy gravy on the side or drizzled right over the top—this is what takes the casserole to brunch superstardom!

How to Serve Overnight Croissant Breakfast Casserole

Garnishes

A scattering of chopped chives or parsley brings a welcome pop of green and a burst of fresh flavor that balances the rich, savory casserole. You can also sprinkle a little extra shredded cheddar or a pinch of paprika on top just before serving for a colorful, tempting finish.

Side Dishes

Pair this hearty main with simple sides to round out your brunch table. A tangy fruit salad, crisp green salad, or just a platter of fresh berries adds brightness and helps cut through the casserole’s creamy richness. For an extra-special breakfast spread, warm up flaky biscuits on the side to sop up every last drop of gravy.

Creative Ways to Present

Try baking the Overnight Croissant Breakfast Casserole in smaller individual ramekins for personalized servings—super cute for brunch parties or holidays. You can also serve small squares as part of a breakfast buffet. For a rustic vibe, bring the whole casserole dish straight to the table and let everyone serve themselves family-style.

Make Ahead and Storage

Storing Leftovers

Cover any leftover casserole tightly with foil or transfer it to an airtight container. It will keep well in the refrigerator for up to three days, making for fast, satisfying breakfasts all week long. Don’t forget to store the gravy separately if you have any left.

Freezing

To freeze the baked casserole, let it cool completely, then wrap tightly in two layers of foil or portion into airtight containers. It can be frozen for up to two months. Thaw overnight in the refrigerator before reheating gently in the oven or microwave for best texture. Freeze the gravy in a separate container, too!

Reheating

Warm individual servings in the microwave, or reheat larger portions in a 350°F oven, covered with foil to keep them moist. The gravy thickens in the fridge, so reheat it slowly on the stove with a splash of milk, stirring until silky smooth. This ensures every bite tastes just as great as the first morning.

FAQs

Can I swap the sausage for another meat?

Absolutely! Bacon, diced ham, or even crumbled cooked turkey sausage will work nicely. Just be sure to cook and drain any meat you use before layering it into your Overnight Croissant Breakfast Casserole.

What’s the best type of croissant to use?

Either large bakery croissants or smaller store-bought minis work well; slightly stale or day-old croissants are ideal, since they soak up the custard without getting mushy.

Do I have to let the casserole soak overnight?

Overnight gives the casserole its fluffiest, most flavorful texture, but if you’re short on time, let it sit for at least four hours before baking to allow the custard to soak in.

Can I make this casserole ahead and freeze it unbaked?

Yes! Assemble the casserole, but don’t bake it. Wrap tightly and freeze for up to two months. Thaw overnight in the fridge before baking as usual—you may need to add 10-15 minutes to the baking time.

How can I make this dish vegetarian?

Simply omit the sausage or replace it with your favorite meat-free sausage, and add sautéed mushrooms, spinach, or peppers for extra flavor and texture in your Overnight Croissant Breakfast Casserole.

Final Thoughts

If you’re looking to create one of those magical breakfast moments, the Overnight Croissant Breakfast Casserole is your ticket. It’s cozy, comforting, and endlessly adaptable—a true crowd-pleaser that frees you up in the morning. Don’t wait for a special occasion; give it a try and turn any day into a brunch-worthy event!

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