Description
This Overnight Croissant Breakfast Casserole is a rich and savory make-ahead dish, featuring buttery croissants, flavorful breakfast sausage, sautéed bell peppers, onions, and gooey Gruyère cheese, all baked together with a luscious egg custard. It’s perfect for feeding a crowd at breakfast, brunch, or holidays, and conveniently assembled the night before for an effortless morning.
Ingredients
Units
Scale
Croissants and Dairy
- 1 pound croissants (about 6 or 7), torn into large bite-sized pieces
- 2 cups whole milk
- 1 cup half and half or heavy cream
- 2 cups Gruyère, grated, divided
- 8 large eggs
- 1 tablespoon unsalted butter (for greasing the baking dish)
Meat
- 3/4 pound breakfast sausage, ground (remove casings if bulk not available)
Vegetables
- 1 small onion, diced
- 1/2 red bell pepper, diced
- 1/2 green bell pepper, diced
Other
- 1 tablespoon olive oil
- 1 teaspoon kosher salt
- 1/2 teaspoon black pepper
- 1/4 teaspoon garlic powder
Instructions
- Prep Croissants – Preheat oven to 425°F. Tear croissants into large bite-sized pieces and spread them in an even layer on a baking sheet. Toast in the oven for 3-5 minutes, watching closely so they don’t overbrown. Remove when golden and let cool.
- Cook Sausage – Heat a large skillet over medium-high. Brown the breakfast sausage, breaking it up as it cooks. Once fully cooked, remove from pan and set aside.
- Sauté Vegetables – Add olive oil to the pan, then add diced onions and both bell peppers with a pinch of salt. Sauté until soft and golden, about 5-10 minutes. Set aside to cool.
- Prepare Baking Dish – Liberally grease a 9×13 baking dish with unsalted butter to prevent sticking.
- Make Egg Custard – In a large bowl, whisk together eggs, whole milk, and half and half or heavy cream. Whisk in the kosher salt, black pepper, and garlic powder until well blended.
- Combine Casserole Mixture – To the bowl, add the browned sausage, sautéed peppers and onions, and 1½ cups of the grated Gruyère. Add the toasted croissants and toss gently until everything is evenly combined and croissants are moistened.
- Assemble and Chill – Transfer the mixture to the prepared baking dish, pouring any excess liquid over the top and spreading into an even layer. Top with a piece of parchment paper, then cover with foil. Refrigerate for at least 1 hour, preferably overnight, to allow flavors to meld.
- Bake Casserole – When ready to bake, bring casserole to room temperature for about 30 minutes. Preheat oven to 350°F. Uncover the casserole, sprinkle the remaining ½ cup of Gruyère over the top, and re-cover with foil.
- Final Baking – Bake covered for 30 minutes. Remove foil and parchment and bake for an additional 10-15 minutes, until the top is golden and no visible liquid remains.
- Rest and Serve – Allow casserole to rest for 15 minutes before slicing and serving, ensuring clean slices and best texture.
Notes
- Leftovers can be stored in a sealed container in the refrigerator for 2-3 days.
- For freezing, wrap leftovers in foil and place in a freezer bag; freeze for up to 4 weeks.
- To reheat, wrap in foil and warm in a 350°F oven for 5-10 minutes, or until heated through.
- You can substitute Gruyère with Swiss or cheddar cheese if preferred.
- Try adding fresh herbs like chives or parsley for extra freshness.
Nutrition
- Serving Size: 1/8th of casserole
- Calories: 520
- Sugar: 5g
- Sodium: 900mg
- Fat: 37g
- Saturated Fat: 18g
- Unsaturated Fat: 16g
- Trans Fat: 0.5g
- Carbohydrates: 30g
- Fiber: 1g
- Protein: 21g
- Cholesterol: 235mg