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Overnight Croissant Breakfast Casserole

Overnight Croissant Breakfast Casserole

Flaky, buttery all-butter croissants soaked in rich savory egg and cream custard, layered with savory browned breakfast sausage and melted Gruyère and sharp cheddar cheese. An effortless make-ahead brunch centerpiece perfect for holidays and cozy weekend mornings.
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Prep Time 20 minutes
Cook Time 45 minutes
Total Time 1 hour 5 minutes
Servings: 8 servings
Calories: 485
Ingredients Method Nutrition

Ingredients
  

Casserole Base & Cheeses
  • 6 large all-butter croissants (day-old preferred), torn into 1.5-inch pieces
  • 1 lb savory halal beef breakfast sausage (or turkey sausage), browned and drained
  • 1.5 cups shredded Gruyère cheese (or Swiss), divided
  • 1.5 cups shredded sharp yellow cheddar cheese, divided
  • 1/3 cup fresh green chives or scallions, thinly sliced
Rich Custard Mixture
  • 8 large farm-fresh eggs
  • 1.5 cups whole milk
  • 1 cup heavy whipping cream
  • 1 tbsp Dijon mustard
  • 1 tsp garlic powder
  • 1/2 tsp onion powder
  • 1/4 tsp freshly grated nutmeg
  • 1 tsp fine sea salt
  • 1/2 tsp freshly cracked black pepper

Method
 

Preparation & Layering
  1. Grease a 9x13-inch ceramic or glass baking dish generously with softened butter.
  2. Spread half of the torn croissant pieces evenly across the bottom of the prepared dish.
  3. Scatter the cooked, drained breakfast sausage crumbles, half of the shredded Gruyère, half of the cheddar cheese, and half of the sliced chives evenly over the croissants.
  4. Top with the remaining torn croissants, pressing down very gently to create a level top layer. Scatter the remaining Gruyère and cheddar cheese across the surface.
Whisking Custard & Chilling
  1. In a large mixing bowl, vigorously whisk together the eggs, whole milk, heavy cream, Dijon mustard, garlic powder, onion powder, nutmeg, sea salt, and black pepper until completely smooth and frothy.
  2. Slowly pour the egg custard mixture evenly over the entire dish, ensuring all croissant pieces are thoroughly moistened.
  3. Cover the dish tightly with plastic wrap and refrigerate for at least 4 hours, or ideally overnight (up to 18 hours), allowing the croissants to soak up the rich custard.
  4. Remove the casserole from the refrigerator 30 minutes before baking to take the chill off. Preheat your oven to 350°F (175°C).
Baking & Serving
  1. Bake uncovered at 350°F (175°C) for 40 to 48 minutes, until the center is puffed and set, the cheeses are bubbling, and the top croissant tips are golden-brown and crispy.
  2. Rest the casserole for 10 minutes at room temperature before slicing. Garnish with the remaining fresh chives and serve warm.

Nutrition

Serving: 1gCalories: 485kcalCarbohydrates: 28gProtein: 22gFat: 34gSaturated Fat: 16gCholesterol: 215mgSodium: 720mgPotassium: 290mgFiber: 2gSugar: 6gVitamin A: 850IUVitamin C: 2mgCalcium: 320mgIron: 2.8mg

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