Overnight Cheesy Bacon Casserole

This hearty overnight cheesy bacon croissant breakfast casserole has been my weekend morning game-changer for years. The perfect balance of crispy edges and custardy center makes this the ultimate holiday or special occasion breakfast when you need something impressive without the morning stress.

I first made this casserole for a family Christmas morning breakfast three years ago, and it's now requested at every holiday gathering. Even my brother-in-law who claims to hate breakfast casseroles goes back for seconds every time.

Ingredients

• Croissants: Use day-old ones for best absorption without becoming mushy
• Bacon: Thick-cut provides more substantial flavor and texture throughout
• Shallots or red onions: Add a sweet aromatic base that balances the richness
• Cheddar and gruyere cheese: Combination creates the perfect balance of sharp tang and nutty creaminess
• Eggs: Provide structure and richness to hold everything together
• Whole milk and heavy cream: Create a velvety custard that transforms the dish
• Salt and pepper: Simple seasonings that enhance without overwhelming the star ingredients

Step-by-Step Instructions

Toast the Croissants:

First toast your halved croissants until golden brown. This crucial step creates a sturdy base that will maintain structure even after soaking in the egg mixture overnight. Watch carefully during the final minutes as they can quickly go from perfectly toasted to burnt.

Prepare the Base:

Tear those toasted croissants into large bite-sized pieces and arrange them evenly in your baking dish. The torn edges create more surface area for the custard to cling to and create those delicious textural contrasts in the final dish.

Cook the Bacon and Aromatics:

Crisp the bacon thoroughly in a skillet until each piece is perfectly rendered. Use the reserved bacon fat to sauté your shallots or red onions until translucent but not browned. This infuses the fat with flavor and prevents any harsh raw onion taste in the finished casserole.

Layer the Components:

Arrange your bacon pieces and sautéed shallots over the croissant base then blanket everything with freshly grated cheese. The layering creates pockets of flavor that will distribute through the casserole as it bakes.

Add the Custard:

Whisk together eggs, milk, cream, and seasonings until completely smooth. Pour this mixture slowly and evenly over the entire casserole allowing it to seep into all the crevices between croissant pieces.

Rest and Bake:

Cover and refrigerate for at least 4 hours but no more than 12. This resting period is essential for the croissants to absorb the custard without breaking down completely. Bake until puffed, golden, and set in the center with no jiggle remaining.

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My absolute favorite part of this recipe is how the edges of the croissants that peek through the top get extra crispy while baking. I sometimes strategically arrange a few pieces to stick up slightly just to create more of these delicious crispy bits. My family fights over these golden corners every single time.

Make-Ahead Options

This casserole was designed for overnight preparation but works beautifully with as little as 4 hours of refrigeration. For busy holiday mornings I often prepare everything the night before so all I need to do is pop it in the oven while we open gifts. You can even prepare all the components separately up to two days in advance keep them refrigerated then assemble and rest the casserole the night before baking.

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Creative Variations

While the classic bacon and cheese version is hard to beat this casserole welcomes customization. For a vegetarian option replace the bacon with sautéed mushrooms and spinach. Breakfast sausage makes a hearty alternative to bacon especially when paired with pepper jack cheese for a slight kick. For a sweet and savory twist add thinly sliced apples between the layers which will soften beautifully during baking and complement the savory bacon.

Serving Suggestions

This casserole is substantial enough to stand alone but pairs wonderfully with a fresh fruit salad to balance the richness. For holiday brunches serve alongside mimosas and a simple green salad dressed with lemon vinaigrette. If serving for dinner add a side of roasted vegetables to create a complete meal. Each square can be garnished with fresh herbs like chives or parsley just before serving to add brightness to each bite.

Storage and Reheating

Leftovers keep beautifully for up to 3 days in the refrigerator. Individual portions reheat perfectly in the microwave for about 1 minute. For maintaining the best texture reheat larger portions in a 325°F oven covered with foil for about 15 minutes. This casserole also freezes well cut into individual portions once completely cooled then wrapped tightly in plastic wrap and foil. Thaw overnight in the refrigerator before reheating.

Frequently Asked Questions

→ Why do I need to toast the croissants?

Toasting the croissants helps them maintain their structure when the custard is added, preventing a soggy texture.

→ Can I substitute the types of cheese?

Yes, you can use a variety of cheeses like white cheddar, Swiss, or even a combination. Just ensure you shred the cheese yourself for a creamier result.

→ What is the best type of milk to use?

Whole milk is recommended for the best texture. Avoid skim milk as it lacks the richness needed for the custard.

→ How long should I refrigerate the casserole before baking?

Refrigerate the casserole for at least 4 hours, but no longer than 12 hours to avoid the croissants breaking down too much.

→ Can I prepare this dish ahead of time?

Absolutely! This casserole is designed to be prepared the night before, making it a convenient option for busy mornings.