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Overnight Croissant Breakfast Casserole

Overnight Croissant Breakfast Casserole

Discover the magic of the Overnight Croissant Breakfast Casserole, a delightful and incredibly easy dish that dramatically simplifies your mornings and elevates your brunch game. This recipe is your secret weapon for hosting guests or simply treating yourself to a gourmet breakfast without the early-morning fuss, making it a truly indispensable addition to your recipe rotation.
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Prep Time 25 minutes
Cook Time 55 minutes
Chilling Time (minimum) 6 minutes
Servings: 6 people
Course: Breakfast, Brunch
Cuisine: American
Ingredients Equipment Method Notes

Ingredients
  

  • 6-8 large croissants day-old or slightly stale (about 8 ounces total)
  • 1 pound breakfast sausage mild or spicy
  • 1 cup finely chopped yellow onion
  • 1/2 cup finely chopped green bell pepper
  • 1/2 cup finely chopped red bell pepper
  • 1 cup shredded cheddar cheese plus more for topping
  • 1 cup shredded Monterey Jack cheese
  • 6 large eggs
  • 3 cups whole milk
  • 1 teaspoon Dijon mustard
  • 1/2 teaspoon salt
  • 1/4 teaspoon black pepper
  • 1/4 teaspoon garlic powder

Equipment

  • 9x13 inch baking dish
  • Large skillet
  • Large bowl
  • Spatula
  • Plastic wrap or aluminum foil

Method
 

  1. Tear the croissants into bite-sized pieces, about 1- to 2-inch chunks. Place them in a single layer in a greased 9x13 inch baking dish. If your croissants are very fresh, you can lightly toast them in the oven for a few minutes or leave them out on the counter for a few hours to achieve a drier texture, which is ideal for absorbing the custard.
    6-8 large croissants
  2. In a large skillet over medium heat, cook the breakfast sausage, breaking it up with a spoon, until browned and cooked through. Drain off any excess grease. Add the chopped yellow onion, green bell pepper, and red bell pepper to the same skillet with the sausage drippings (or add a little olive oil if needed). Cook, stirring occasionally, until the vegetables are softened, about 5-7 minutes.
    1 pound breakfast sausage, 1 cup finely chopped yellow onion, 1/2 cup finely chopped green bell pepper, 1/2 cup finely chopped red bell pepper
  3. Sprinkle the cooked sausage and vegetable mixture evenly over the torn croissant pieces in the baking dish. Next, evenly distribute the shredded cheddar cheese and Monterey Jack cheese over the sausage and vegetables.
    1 cup shredded cheddar cheese, 1 cup shredded Monterey Jack cheese
  4. In a large bowl, whisk together the 6 large eggs, 3 cups of whole milk, 1 teaspoon of Dijon mustard, 1/2 teaspoon of salt, 1/4 teaspoon of black pepper, and 1/4 teaspoon of garlic powder until well combined and frothy. The Dijon mustard adds a subtle tang that enhances the overall flavor without making the casserole taste like mustard.
    6 large eggs, 3 cups whole milk, 1 teaspoon Dijon mustard, 1/2 teaspoon salt, 1/4 teaspoon black pepper, 1/4 teaspoon garlic powder
  5. Pour the egg and milk mixture evenly over the ingredients in the baking dish, ensuring that all the croissant pieces are moistened. Gently press down on the croissants with a spatula to help them absorb the liquid.
  6. Cover the baking dish tightly with plastic wrap or aluminum foil. Refrigerate the casserole for at least 6 hours, or preferably overnight. This crucial step allows the croissants to fully absorb the custard, creating an incredibly tender and flavorful casserole.
  7. When you're ready to bake, preheat your oven to 350°F (175°C). Remove the plastic wrap from the baking dish, and if desired, sprinkle a little extra shredded cheddar cheese over the top for an even more decadent finish. Bake for 45-55 minutes, or until the casserole is golden brown, puffed up, and a knife inserted into the center comes out clean.
    1 cup shredded cheddar cheese
  8. Let the Overnight Croissant Breakfast Casserole rest for about 10 minutes before slicing and serving. This allows the custard to set fully, making it easier to serve and ensuring a perfect texture.

Notes

Storing Leftovers: Once cooled, cover tightly and refrigerate for up to 3-4 days. Reheating (Oven Recommended): Preheat to 325°F (160°C). Tent with foil and bake 15-25 min for portions, 30-45 min for larger. Reheating (Microwave): Quick option for a single serving on medium power for 1-2 min.