Overnight Croissant Casserole

An incredibly rich, make-ahead Overnight Croissant Casserole packed with buttery croissants, sharp cheddar, and fresh herbs in a velvety egg custard.

Why This Recipe Works:

• The laminated layers of the croissants trap the egg custard, creating a texture that is custardy on the bottom and crispy on top.
• Letting the casserole rest overnight allows the starch molecules to fully hydrate, ensuring even baking without dry pockets.
• Sharp cheddar and fresh herbs cut through the rich, buttery pastry, balancing the flavor profile beautifully.

Last December, I hosted a holiday brunch and tried to slice cold, day-old croissants with a dull serrated knife, tearing them until my thumbs were slick with butter and my kitchen counter looked like a pastry crime scene.

I learned this the hard way.

Most breakfast bakes end up as a soggy, sponge-like mass because people dump a massive volume of liquid egg mixture over stale bread without considering the protein matrix. When you saturate starch too quickly, the proteins in the egg cannot coagulate properly, leaving you with a wet, weeping mess at the bottom of your baking dish.

I learned this after testing six different custard ratios with various grocery store brands.

Trust me on this one, the secret lies in using day-old, high-quality croissants that you tear by hand. This creates jagged edges that catch the custard while leaving the tops beautifully crisp and golden.

No fancy equipment needed.

Just grab a baking dish, whisk up your custard, and let the fridge do all the heavy lifting overnight. It is just as effortless as prepping Overnight Oats the night before, making it hands down the easiest way to feed a hungry crowd.

Overnight Croissant Casserole

• Publisher Storied Skillet
• Cuisine American
• Category Breakfast, Brunch
• Prep Time 15 minutes
• Cook Time 45 minutes
• Servings 8 servings
• Calories 420 calories
• Rating 4.8 5478
• Tags croissant breakfast bake, make ahead brunch, egg casserole, fresh herbs

Ingredients

• 6 large day-old croissants, torn into bite-sized pieces
• 1.5 cups sharp cheddar cheese, shredded
• 1 cup Gruyère cheese, shredded
• 8 large eggs
• 1.5 cups whole milk
• 1 cup heavy cream
• 1 tsp Diamond Crystal kosher salt
• 0.5 tsp freshly cracked black pepper
• 2 tbsp fresh chives, finely chopped
• 1 tbsp fresh thyme leaves
• 0.5 tsp garlic powder

Directions

1. Grease a 9x13-inch baking dish with butter.
2. Tear the croissants into bite-sized pieces and spread them evenly in the prepared baking dish.
3. Sprinkle the shredded cheddar and Gruyère cheeses evenly over the croissant pieces, tucking some cheese into the crevices.
4. In a large bowl, whisk together the eggs, whole milk, heavy cream, Diamond Crystal kosher salt, black pepper, garlic powder, chives, and thyme until fully combined.
5. Pour the egg mixture evenly over the croissants and cheese, pressing down gently with a spatula to ensure all the pastry pieces are submerged.
6. Cover the dish tightly with plastic wrap and refrigerate for at least 4 hours, or preferably overnight.
7. Preheat your oven to 375°F (190°C). Remove the casserole from the refrigerator and let it sit at room temperature for 20 minutes while the oven preheats.
8. Bake uncovered for 40 to 45 minutes, until the top is puffed and golden brown, and the center is set. Let cool for 10 minutes before serving.

Notes

• I highly recommend using Diamond Crystal kosher salt; if you are using fine table salt, cut the measurement in half to 0.5 teaspoon to avoid an over-salted custard.
• Whole milk and heavy cream are essential here because their fat content stabilizes the egg protein matrix, preventing the custard from curdling or weeping liquid during baking.
• Keep a close eye on the oven during the last 10 minutes of baking; if the croissant tops are browning too quickly, tent the dish loosely with aluminum foil to prevent them from burning while the center finishes setting.
• After a day in the fridge, the baked croissants will lose their initial crispness as they absorb residual moisture, but the flavors will actually deepen and meld together beautifully.

Serving Suggestions

This savory bake is incredibly rich, so pairing it with bright, acidic sides helps balance the plate and completes your morning spread.

• A crisp green salad tossed in a zesty lemon vinaigrette.
• A bowl of fresh berries or our vibrant Watermelon Feta Salad.
• Crispy bacon strips or savory breakfast sausage links.
• A hot cup of coffee or a refreshing Iced Strawberry Latte.
• Serve it alongside a sweet option like our Blueberry French Toast Casserole for the ultimate brunch.

Storage and Reheating

Store any leftovers in an airtight container in the refrigerator for up to three days. The croissants will naturally soften over time, but the custard remains wonderfully rich.

Do not use a microwave to reheat this dish. It turns the buttery pastry into a rubbery, sad disappointment.

Instead, place slices on a baking sheet and warm them in a 350°F (175°C) oven for about ten minutes. This revives the crispy edges and melts the cheese perfectly.

Ingredient Substitutes

If you need to swap things out, here are the best tested alternatives that won't ruin the texture of your bake.

1. Croissants: If you cannot find croissants, brioche or challah bread make excellent substitutes, though you will lose some of that signature buttery lamination.
2. Gruyère Cheese: Swiss cheese, Fontina, or Gouda can be used in place of Gruyère for a similarly smooth, melty texture.
3. Heavy Cream: You can substitute the heavy cream with half-and-half, but avoid using skim milk as the custard will become too watery.
4. Fresh Herbs: If fresh herbs aren't available, use one-third of the amount of dried herbs (such as dried thyme or parsley).

I hope this cozy bake brings as much joy to your brunch table as it does to mine. Let me know how yours turns out, and don't forget to pour yourself an extra cup of coffee while it bakes!