Description
This Overnight Croissant Breakfast Bake is a delicious make-ahead dish featuring toasted buttery croissants layered with sautéed mushrooms, spinach, and a rich custard of eggs, milk, and cream, all topped with melted Gruyere and Parmesan cheese. Perfect for a hearty breakfast or brunch, this casserole is prepped the night before and baked fresh in the morning for a comforting and flavorful start to your day.
Ingredients
Scale
Bakery
- 5 to 7 large croissants, sliced in half lengthwise
Vegetables & Aromatics
- 1 sweet onion, diced
- 2 garlic cloves, minced
- 10 ounces cremini mushrooms, chopped
- 8 ounces fresh baby spinach
- Kosher salt and pepper, to taste
- 2 tablespoons unsalted butter
- 8 large eggs
- 2 ½ cups milk
- 1 cup heavy cream
- 8 ounces Gruyere cheese, freshly grated
- Parmesan cheese, for topping
- Fresh chopped parsley, for topping
Dairy & Eggs
Herbs
Instructions
- Preheat and toast croissants: Preheat the oven to 450 degrees F. Place the croissants cut-side up on a baking sheet and bake for 5 to 8 minutes until toasty. Remove and let cool slightly, then chop or tear into pieces.
- Sauté vegetables: Heat the butter in a large skillet over medium-low heat. Add diced onions and minced garlic, cooking for 5 minutes until softened. Add chopped mushrooms and cook for another 5 minutes until juicy. Stir in the spinach and cook until wilted. Season with kosher salt and pepper.
- Prepare baking dish and combine ingredients: Brush a 9×13 baking dish with melted butter. Combine the toasted croissant pieces with the sautéed vegetable mixture in the dish and toss until well mixed.
- Mix custard: In a large bowl, whisk together eggs, milk, heavy cream, salt, and pepper. Stir in 1 cup of freshly grated Gruyere cheese and optionally add fresh chopped herbs such as parsley or chives for extra flavor.
- Assemble bake: Pour the egg mixture over the croissant and vegetable mixture in the baking dish. Press the croissants gently to ensure they absorb the custard evenly.
- Chill overnight: Cover the dish tightly with plastic wrap and refrigerate for at least 8 hours or overnight to allow flavors to meld and the croissants to soak up the custard.
- Preheat and bake: The next morning, preheat the oven to 350 degrees F. Remove the dish from the fridge about 30 minutes before baking to take the chill off. Remove the plastic wrap and sprinkle the remaining Gruyere cheese evenly on top.
- Bake and garnish: Bake uncovered for 45 minutes until the custard is set and the top is golden brown. Once baked, sprinkle extra Parmesan cheese and fresh chopped parsley over the top before serving.
- Serve: Serve warm as a delicious and filling breakfast or brunch dish.
Notes
- This overnight breakfast bake is made with toasted buttery croissants, spinach, mushrooms, eggs and freshly grated Gruyere cheese.
- Prepare it the night before and bake fresh in the morning for a stress-free breakfast.
- Feel free to add fresh herbs like parsley and chives to the egg mixture to enhance flavor.
- You can substitute Swiss cheese for Gruyere if desired.
- Make sure to press the croissants well into the custard to absorb maximum flavor and moisture.
- Letting the bake rest outside the fridge briefly before baking helps even cooking.
Nutrition
- Serving Size: 1 slice (approx. 1/8th of casserole)
- Calories: 420 kcal
- Sugar: 4 g
- Sodium: 320 mg
- Fat: 28 g
- Saturated Fat: 15 g
- Unsaturated Fat: 10 g
- Trans Fat: 0.5 g
- Carbohydrates: 27 g
- Fiber: 2 g
- Protein: 15 g
- Cholesterol: 220 mg
