This Overnight Croissant Breakfast Casserole is about to become your secret weapon for stress-free mornings. There’s nothing quite like waking up knowing breakfast is already done, just waiting in the fridge for its moment to shine.
I remember those chaotic Sunday mornings at Grandma’s farm when aunts, uncles, and cousins would arrive for breakfast after church. Grandma always had something special waiting – usually assembled the night before while she hummed along to the radio. She’d pull a golden, bubbling casserole from the oven, and the whole kitchen would fill with the smell of butter, cheese, and sausage. Everyone gathered around that old farmhouse table, and for a moment, the world felt perfectly right. That’s exactly what this overnight croissant breakfast casserole does – it brings people together without the morning rush. Time to get our hands floury.
What Makes This Overnight Croissant Breakfast Casserole So Special
Betty’s always believed that the best breakfast recipes are the ones that let you actually enjoy your morning instead of slaving over the stove. This casserole captures everything she learned from years of feeding hungry families – it’s practical, delicious, and foolproof. The buttery croissants soak up all that creamy, savory goodness overnight, creating a texture that’s somewhere between French toast and a savory bread pudding.
Here’s why this recipe belongs in your regular rotation:
Uses ingredients you likely have – no specialty shopping required for this comforting breakfast
Comes together in just 30 minutes the night before, leaving mornings completely stress-free
Feeds 12 hungry people from one 9×13 dish, perfect for holidays and gatherings
Delivers consistently golden, crowd-pleasing results every single time you bake it
Includes homemade sausage gravy that takes this from good to absolutely unforgettable
Adapts easily with gluten-free substitutions without sacrificing that indulgent flavor
Ingredient Spotlight
Butter Croissants: These flaky pastries are the star of the show, bringing a rich, buttery foundation that elevates this beyond ordinary breakfast casseroles. I always choose day-old croissants because they soak up the egg mixture perfectly without becoming soggy.
Breakfast Sausage: The mild-flavored sausage provides savory depth and hearty protein that makes this casserole truly satisfying. Betty always browns hers completely and saves some of that flavorful fat for the gravy – nothing goes to waste in her kitchen.
Cheddar Cheese: Sharp cheddar adds a tangy, melty richness that complements the buttery croissants beautifully. I prefer shredding my own from a block rather than using pre-shredded, as it melts more smoothly.
Heavy Whipping Cream: This creates the luxurious, custardy texture that holds everything together. In my kitchen, I prefer full-fat cream because it produces that velvety consistency that makes every bite feel special.
Eggs: Six large eggs bind all the ingredients while adding protein and creating that classic breakfast casserole structure. Betty’s tip: Always whisk them thoroughly with the milk mixture for even distribution.
Dry Mustard Powder: This secret ingredient adds subtle depth without overpowering the other flavors. I’ve learned that a little dry mustard enhances the cheese and sausage in ways fresh mustard simply can’t.
Whole Milk: Using whole milk in both the casserole and gravy creates a richer, more cohesive flavor throughout the dish. After years of testing, I’ve found that skim or low-fat milk just doesn’t deliver the same comforting result.
How to Make Overnight Croissant Breakfast Casserole
Step 1. I always start by heating the olive oil in a large skillet over medium heat – once it shimmers, add the chopped onions and sauté until they turn soft and translucent, about 3-4 minutes.
Step 2. Add the breakfast sausage to the skillet and cook until completely browned, breaking it apart with a wooden spoon as it cooks, then drain the fat but save about 2 tablespoons for your gravy later.
Step 3. Betty’s tip: Let the sausage mixture cool for about 10-15 minutes while you prepare the croissants – this prevents the eggs from cooking when you combine everything.
Step 4. Tear the croissants into bite-sized pieces (I aim for roughly 2-inch chunks) and place them in a large bowl with the cooled sausage mixture and shredded cheddar cheese, tossing everything together.
Step 5. Spread the croissant mixture evenly in a greased 9×13-inch baking dish (use butter or cooking spray), making sure to distribute the sausage and cheese throughout – this ensures every serving has all the good stuff.
Step 6. In another bowl, whisk together the eggs, heavy cream, 1/2 cup milk, dry mustard, salt, pepper, paprika, and garlic powder until completely smooth and well combined.
Step 7. Pour the egg mixture evenly over the croissant mixture in the baking dish, gently pressing down with a spatula to help the croissants absorb the liquid, then cover tightly with plastic wrap or a lid and refrigerate overnight (or at least 8 hours).
Step 8. The next morning, preheat your oven to 350°F and bake the uncovered casserole for 35-45 minutes until the top turns golden brown and the center is set when you gently shake the dish – it should no longer jiggle but shouldn’t be dried out.
Keeping This Breakfast Casserole Fresh
This casserole actually needs to be refrigerated overnight before baking – that’s when the magic happens. The croissants soak up all that savory, eggy goodness, transforming into something incredibly tender and flavorful. I typically assemble mine in a glass baking dish with a tight-fitting lid, though plastic wrap works perfectly fine too. The assembled casserole can sit in the fridge for up to 24 hours before baking, giving you flexibility if you want to prep even further ahead.
Once baked, leftovers stay fresh in the refrigerator for up to 3 days when stored in an airtight container. Betty’s storage method works well because she portions out individual servings before refrigerating – this makes reheating for quick weekday breakfasts so much easier. The casserole maintains its texture remarkably well, though you might notice the top loses a bit of its crispness after a day or two.
For the best texture, I reheat by covering individual portions with a damp paper towel and microwaving for 60-90 seconds, or by warming in a 300°F oven for about 10 minutes. The microwave is faster, but the oven brings back some of that golden crispness on top. The gravy reheats beautifully on the stovetop with a splash of milk to loosen it up, or in the microwave in 30-second intervals, stirring between each.
Overnight Croissant Breakfast Casserole
This make-ahead breakfast casserole combines buttery croissants with savory sausage, cheddar cheese, and a rich egg custard, topped with homemade sausage gravy.
Heat olive oil in a large skillet over medium heat. Add chopped onions and sauté until soft and translucent, about 3-4 minutes.
Add breakfast sausage to the skillet and cook until completely browned, breaking it apart as it cooks. Drain the fat but reserve 2 tablespoons for the gravy.
Let the sausage mixture cool for about 10-15 minutes while preparing the croissants.
Tear croissants into bite-sized pieces (about 2-inch chunks) and place in a large bowl with the cooled sausage mixture and shredded cheddar cheese. Toss to combine.
Spread the croissant mixture evenly in a greased 9×13-inch baking dish (use butter or cooking spray).
In another bowl, whisk together eggs, heavy cream, 1/2 cup milk, dry mustard, salt, pepper, paprika, and garlic powder until smooth and well combined.
Pour the egg mixture evenly over the croissant mixture, gently pressing down with a spatula to help absorption. Cover tightly with plastic wrap or lid and refrigerate overnight (at least 8 hours).
The next morning, preheat oven to 350°F (175°C). Remove cover from casserole and bake for 35-45 minutes until the top is golden brown and the center is set (should not jiggle when gently shaken).
While casserole bakes, prepare gravy: Melt 2 tablespoons butter with reserved sausage fat in a saucepan. Whisk in flour and cook for 1 minute, stirring constantly.
Gradually add remaining 2 1/2 cups milk to the gravy while whisking constantly. Continue stirring until gravy thickens to desired consistency. Season with salt and pepper to taste.
Let casserole rest for 10 minutes before serving. Serve hot with homemade sausage gravy on the side.
Notes
Must refrigerate overnight for proper setting. Save sausage fat for gravy. For gluten-free version, use gluten-free croissants or bread and gluten-free flour blend. Leftovers store covered in refrigerator for up to 3 days.
Perfect Partners for Overnight Croissant Breakfast Casserole
Crispy Smashed Potatoes with Garlic Herbs: These golden, crispy potatoes add that satisfying crunch and familiar diner-style comfort that complements the soft, custardy texture of the casserole perfectly.
Roasted Sweet Potatoes with Cinnamon Honey: For a touch of sweetness that balances the savory richness, these caramelized sweet potatoes bring bright colors and autumn flavors to your breakfast table.
Garlic Roasted Sweet Potatoes: The savory garlic version pairs wonderfully if you prefer keeping the entire meal in the savory spectrum, with caramelized edges that everyone loves.
Fresh Fruit Salad: A bowl of seasonal berries, melon, and grapes provides a refreshing, sweet contrast to the rich, savory casserole while adding bright colors to your breakfast table.
Simple Green Salad: For brunch gatherings, a light salad with mixed greens, cherry tomatoes, and a tangy vinaigrette balances the richness and makes the meal feel more complete.
Baked Salmon and Asparagus Sheet Pan: During spring holidays, roasted asparagus with a squeeze of lemon brings an elegant, slightly bitter note that cuts through the buttery richness beautifully.
Orange Juice and Coffee: No breakfast is complete without these classic beverages – the citrus brightens everything while hot coffee provides that essential morning comfort.
FAQs
Can I use regular bread instead of croissants? I recommend sticking with croissants for that signature buttery richness, but if you’re in a pinch, brioche or challah bread makes excellent substitutes that maintain the indulgent texture this recipe is known for.
How do I prevent the casserole from becoming soggy? Betty’s solution is to tear the croissants into larger, bite-sized pieces rather than small bits, and to make sure the sausage mixture has cooled completely before combining – this prevents excess moisture from making things mushy.
Can I make this casserole gluten-free? Many home cooks find success with gluten-free croissants or buttery gluten-free bread, paired with a gluten-free flour blend for the gravy – just ensure all your ingredients are certified gluten-free, including the sausage seasoning.
Can I assemble and freeze this before baking? To prevent texture issues, I recommend freezing only the baked casserole – assemble, refrigerate overnight, bake, cool completely, then freeze in portions for up to 2 months and reheat as needed.
What if I don’t have heavy cream? The best approach I’ve tested is using half-and-half instead, though you’ll sacrifice a bit of that luxurious richness – avoid using all milk as it makes the texture less custardy.
Can I add vegetables to this casserole? I’ve found that sautéed bell peppers, mushrooms, or spinach work beautifully when added with the sausage mixture – just make sure to cook off excess moisture from the vegetables first to prevent a watery casserole.
