Elevate your morning routine with this Easy Overnight Croissant Breakfast Casserole. This dish takes the concept of a savory bread pudding and upgrades it with buttery, flaky croissants. Instead of dense bread, the croissants create a light, airy texture that soaks up the rich egg custard while maintaining a crisp, golden top.
Packed with savory sausage, fresh spinach, and nutty Gruyere cheese, this casserole is elegant enough for a holiday brunch but simple enough for a weekend treat. The “overnight” preparation means you do the work the night before, allowing you to wake up to a stress-free, delicious breakfast.
Why You’ll Love This Recipe
Buttery Perfection
The croissants add a richness that standard bread simply cannot match. The contrast between the soft, custard-soaked interior and the crispy, flaky peaks is divine.
Effortless Entertaining
Assemble it in the evening and bake it while you brew coffee. If you are looking for a healthy, grab-and-go option to round out your brunch table, these Nut & Seed Energy Cookies are a fantastic addition.

Ingredients
- 6 large croissants, torn into pieces
- 1 lb breakfast sausage, cooked
- 2 cups fresh spinach
- 2 cups Gruyere cheese, shredded
- 8 large eggs
- 1 cup heavy cream
- 1 cup milk
- 1/2 tsp garlic powder
Instructions
- Grease baking dish. Cook sausage and wilt spinach.
- Layer half the croissants, sausage mix, and cheese in dish.
- Top with remaining croissants.
- Whisk eggs, cream, milk, and garlic powder. Pour over.
- Refrigerate overnight.
- Bake at 350°F for 45-50 mins until set.
- Serve warm.
Ingredient Highlights & Substitutions
Essential Ingredients
Large Croissants (stale/day-old work best). Breakfast Sausage (browned and crumbled). Fresh Spinach. Gruyere Cheese (shredded). Eggs. Heavy Cream and Milk. Garlic Powder.
Smart Substitutions
You can substitute Swiss or white cheddar for the Gruyere. Bacon or diced ham work well in place of sausage. If you don’t have croissants, brioche or challah bread are good alternatives.
Step-by-Step Instructions
Prep Phase
Grease a 9×13 inch baking dish. Tear the croissants into large, bite-sized pieces. Brown the sausage in a skillet; stir in the spinach at the end to wilt it.
Cooking Phase
Place half of the croissant pieces in the dish. Top with the sausage mixture and half the cheese. Layer the remaining croissants on top. Whisk the eggs, cream, milk, and spices in a bowl. Pour evenly over the casserole. Press down gently to ensure absorption. Cover and refrigerate overnight (or at least 4 hours). Preheat oven to 350°F (175°C) and bake for 45-50 minutes until puffed and golden.
Pro Tips for Perfect Results
Technique Secrets
Don’t shred the croissants too small; keep the chunks substantial for better texture. When arranging the top layer, ensure some crusty edges are pointing up to get extra crispy in the oven.
Common Mistakes to Avoid
Underbaking is the main risk. The center should be set, not liquid. If the top is browning too fast, tent it with foil for the last 15 minutes.
Serving Ideas & Pairings
Presentation & Plating
Serve warm squares garnished with fresh herbs.
Pairing Suggestions
Fresh fruit salad and mimosas or orange juice complete the meal.
Frequently Asked Questions
Q1? Can I use fresh croissants?
Yes, but leave them out on the counter for a few hours to dry out slightly so they absorb the custard better.
Q2? Can I make it vegetarian?
Absolutely. Omit the sausage and add sautéed mushrooms and onions.
Q3? How long does it keep?
Leftovers can be stored in the fridge for 3 days and reheated in the oven.
| Nutrient | Amount per Serving |
|---|---|
| Calories | 510 kcal |
| Total Fat | 35g |
| Saturated Fat | 18g |
| Cholesterol | 240mg |
| Sodium | 850mg |
| Carbohydrates | 28g |
| Dietary Fiber | 2g |
| Protein | 18g |
Conclusion
The Easy Overnight Croissant Breakfast Casserole transforms breakfast into a luxurious event. With minimal effort, you get a buttery, savory, and deeply satisfying meal that everyone will love.
