Overnight Croissant Breakfast Casserole

It was a crisp autumn morning, the kind where you crave something warm, comforting, and utterly delicious without lifting a finger the moment your alarm sounds. I remember those busy weekdays vividly, juggling morning routines, packing lunches, and still wishing for a special breakfast. This yearning sparked the idea for my now-famous Overnight Croissant Breakfast Casserole.

I pictured golden, flaky croissants, soaked in a sweet, custardy mixture, bursting with berries and baked to perfection while I slept. The concept was simple: prepare everything the night before, slide it into the oven in the morning, and wake up to an irresistible aroma filling the house. This dish became my secret weapon for stress-free entertaining and luxurious weekend brunches alike.

Indeed, the first time I served this glorious Overnight Croissant Breakfast Casserole, the oohs and aahs from my family confirmed its instant classic status. It’s truly a magical way to start any day, transforming simple ingredients into an extraordinary experience. You too can conquer your mornings with this incredible make-ahead marvel!

Why You’ll Love This Overnight Croissant Breakfast Casserole Recipe

This overnight version guarantees maximum flavor with minimal morning effort.​

• Make-ahead friendly: Assemble in 20 minutes the night before; just bake in the morning.​
• Uses leftover croissants: Day-old croissants become tender, custardy, and irresistible when baked with eggs and cheese.​
• Savory bistro flavor: Ham, Gruyère, and roasted peppers add a French café vibe that guests love.​
• Feeds a crowd: One 9×13 pan comfortably serves 8–10 people, perfect for holidays or potlucks.​
• Completely customizable: Swap ham for bacon, veggies, or make it vegetarian with extra greens and cheese.​

If you want to make this even more from-scratch, try using your own dough following a Homemade Croissants step-by-step guide before turning them into this casserole.

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Ingredients You’ll Need

This recipe leans savory with enough richness to feel indulgent without being heavy.

• 6–7 medium butter croissants, preferably a day old, torn into large pieces​
• 1 tablespoon butter, for greasing dish​
• 1 cup diced cooked ham (thick-cut, about 1/4-inch pieces)​
• 1/2 cup jarred roasted red peppers, drained and chopped
• 4 green onions, thinly sliced (white and green parts)​
• 1 1/2 cups shredded Gruyère cheese
• 1/2 cup shredded mozzarella cheese

Egg custard:

• 8 large eggs​
• 1 3/4 cups half-and-half or whole milk (or a mix)​
• 1 teaspoon Dijon mustard​
• 1/2 teaspoon garlic powder
• 1/2 teaspoon onion powder
• 1/2 teaspoon smoked paprika
• 3/4 teaspoon kosher salt, or to taste​
• 1/2 teaspoon freshly ground black pepper​

Topping:

• 2 tablespoons grated Parmesan
• 1 tablespoon chopped fresh parsley or chives, for serving

For a sweeter spin using croissants, you can also look at berry-focused casseroles similar to a Berry Croissant Breakfast Bake for inspiration.

Step-by-Step Instructions

1. Prep the dish and croissants

   • Grease a 9×13-inch baking dish with butter.​

   • Tear croissants into large bite-size pieces and spread evenly in the dish.​

2. Optional: Lightly toast croissants

   • For extra texture, bake croissant pieces on a sheet pan at 350°F (175°C) for 8–10 minutes until lightly crisp, then cool and return them to the dish.​

3. Layer ham, veggies, and cheese

   • Sprinkle the diced ham evenly over the croissants.​

   • Distribute roasted red peppers and green onions on top.​

   • Sprinkle Gruyère and mozzarella evenly over everything.​

4. Whisk the custard

   • In a large bowl, whisk eggs until smooth.​

   • Add half-and-half, Dijon, garlic powder, onion powder, smoked paprika, salt, and pepper; whisk until well combined.​

5. Assemble and soak overnight

   • Slowly pour the custard evenly over the casserole, making sure to moisten all croissant pieces; gently press down any dry pieces so they contact the liquid.​

   • Cover tightly with plastic wrap or foil and refrigerate at least 8 hours or overnight (up to about 12 hours).​

6. Bring to room temperature and bake

   • In the morning, remove the casserole from the fridge and let it sit at room temperature for 20–30 minutes while the oven preheats to 350°F (175°C).​

   • Remove the cover, sprinkle Parmesan over the top, and place the dish on a sheet pan to catch any drips.​

   • Bake uncovered for 40–50 minutes, until puffed, golden, and the center is set (a knife inserted in the middle should come out without wet egg).​

7. Rest and serve

   • Let the casserole rest 10–15 minutes so the custard sets and slices cleanly.​

   • Sprinkle with fresh parsley or chives, cut into squares, and serve warm.​

For a sweeter, dessert-leaning croissant bake, you could adapt this method using chocolate and cream cheese similar to an Easy Chocolate Croissant Bake

How to Serve Overnight Croissant Breakfast Casserole

This casserole is best served warm, shortly after its brief resting period so the interior stays tender and custardy but firm enough to hold its shape. Slice into generous squares and use a spatula to lift portions, preserving the layers of croissant, ham, and cheese.​

To build a full brunch spread, pair each serving with:

• A bright side salad of arugula or mixed greens lightly dressed with lemon vinaigrette.​
• A platter of fresh fruit—berries, melon, or citrus—to cut through the richness.​
• Crispy bacon or breakfast sausage if you want extra protein for hearty appetites.​

This dish also pairs beautifully with hot coffee, lattes, or mimosas for a relaxed weekend setting. If you’re feeding a crowd, keep the baking dish in a warm (around 200°F / 95°C) oven between servings so each slice stays pleasantly hot without overbaking. For variety on a buffet table, add a sweet croissant-based bake—something similar to a berry or chocolate croissant breakfast bake—so guests can choose savory, sweet, or both.​

How to Store Overnight Croissant Breakfast Casserole

Leftovers store very well and make quick, satisfying breakfasts for days. Once the casserole has cooled to room temperature, cover the dish tightly or transfer individual portions to airtight containers before refrigerating. Properly stored, the casserole keeps for about 3–4 days in the refrigerator with good flavor and texture.​

To reheat single servings quickly, use the microwave on medium power for 45–60 seconds, checking so they warm through without drying out. For the best texture, especially for the topping, reheating in a 325–350°F (165–175°C) oven or toaster oven for 10–15 minutes restores the slight crispness on top while keeping the inside soft. For longer storage, many croissant casseroles can be frozen after baking and cooling completely; wrap tightly and freeze for up to 2–3 months, then thaw overnight in the fridge and reheat until hot in the center.​

Sweet croissant bakes such as berry or chocolate versions follow similar storage and reheating guidelines, so you can prep several styles ahead for busy weeks.​

Tips to Make Overnight Croissant Breakfast Casserole

Attention to a few small details is key to an evenly cooked, flavorful casserole.​

• Use bakery-style croissants: Medium or large, flaky croissants from the bakery section absorb custard best and deliver great texture.​
• Slightly stale is ideal: Day-old croissants soak up the custard without turning mushy, especially after a brief toasting.​
• Submerge but don’t drown: Gently press croissant pieces into the custard so most are moistened, leaving some tips exposed for crisp, golden edges.​
• Don’t oversoak time-wise: Aim for 8–12 hours; soaking much longer can cause the croissants to break down too much.​
• Season the custard well: Custard is the flavor backbone—salt, pepper, Dijon, and spices ensure it doesn’t taste flat.​
• Check doneness in the center: The middle is the last part to set; a knife or toothpick should come out without liquid egg but with moist crumbs.​
• Rest before slicing: A short rest helps the custard finish setting and makes cutting and serving neater.​

These techniques translate easily to sweet adaptations like berry or chocolate croissant bakes, where good croissants, proper soaking, and careful baking produce that perfect custardy texture every time.​

Variations of Overnight Croissant Breakfast Casserole

Once you master the basic method, changing flavors is simple and fun.​

• Classic bacon & cheddar: Swap the ham and peppers for crisp bacon and sharp cheddar, keeping the same custard base.​
• Sausage and spinach: Use cooked breakfast sausage, sautéed onion, and fresh spinach for a hearty, veggie-packed version.​
• Southwest-style: Add chorizo or spicy sausage, diced green chiles, pepper jack cheese, and a sprinkle of cilantro; serve with salsa and sour cream.​
• Mixed berry & cream cheese: Omit ham and savory spices; instead, layer berries and dollops of sweetened cream cheese with a lightly sweet custard.​
• Chocolate-hazelnut twist: Spread croissants with chocolate-hazelnut spread, omit savory elements, and bake in a vanilla custard for a dessert-leaning brunch.​

If dessert-style brunch is your favorite, an Easy Chocolate Croissant Bake shows how well croissants pair with chocolate in an oven-baked, custardy format.​

FAQs

Q1: Can I skip the overnight chill and bake it right away?
You can bake after a 30–60 minute soak, but the texture will be less custardy and uniform than a true overnight version; overnight chilling gives the best results.​

Q2: Can I make this casserole without ham for a vegetarian option?
Yes, simply omit the ham and increase the vegetables and cheese—spinach, mushrooms, roasted peppers, and extra Gruyère all work well.​

Q3: What if my croissants are very fresh and soft?
Either toast them lightly first or add an extra croissant so they don’t become too soft in the custard.​

Q4: How do I keep the top from overbrowning while the center finishes baking?
If the top browns too quickly, tent loosely with foil for the last 10–15 minutes to protect the crust while the center sets fully.

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