This overnight croissant breakfast casserole began as a way to rescue day-old pastries and turned into one of my most requested weekend dishes. I discovered the combination on a chilly Sunday when I had five slightly stale croissants left from a bakery run and a pound of leftover breakfast sausage. The buttery, laminated layers of the croissants soak up the rich custard overnight and bake into a tender, golden-top dish that tastes indulgent without fuss. It’s the kind of recipe that fills the kitchen with warm, inviting aromas and gathers family around the table on slow mornings. What makes this version special is the balance of textures and flavors: crisp, browned edges with a custardy interior, pockets of savory sausage, and melted cheddar that stretches when you cut into a piece. I like to use day-old croissants because they hold shape while absorbing the egg mixture; the result is less soggy and more custard-like. This preparation is excellent for holidays, overnight guests, or when you want to set the table with minimal morning work. The casserole reheats beautifully and can be adapted to what you have on hand, which is why it’s become my go-to for feeding a crowd.

Ingredients

• Day-old croissants: 5 large croissants torn into large chunks. Day-old or slightly stale croissants soak up custard better; seek butter-rich bakery croissants for best flavor.
• Ground sausage: 1 pound cooked and drained. Use your favorite breakfast sausage or turkey sausage for a leaner option; cook until no pink remains and drain excess fat.
• Cheddar cheese: 1 cup shredded. Sharp cheddar adds tang and melts well; use pre-shredded for convenience or shred a block for creamier melting.
• Large eggs: 6 eggs whisked with milk to create the custard base. Room-temperature eggs combine more evenly with milk for a smooth texture.
• Whole milk: 2 cups. Whole milk yields a richer custard; you can substitute half-and-half for an even creamier result or low-fat milk for fewer calories.
• Seasonings: 1 teaspoon salt, 1/2 teaspoon black pepper, 1/2 teaspoon garlic powder, and 1/2 teaspoon onion powder. These modest seasonings build savory depth without overpowering the buttery croissant flavors.
• Garnish (optional): Fresh chopped parsley for brightness and visual contrast when serving.

Instructions

Prepare the base: Grease a 9 by 13-inch baking dish with cooking spray or softened butter. Tear 5 large croissants into large, irregular chunks and layer them evenly across the dish. The uneven pieces create texture as some edges brown more crisply during baking. Add the protein and cheese: Cook 1 pound of ground sausage in a skillet over medium heat until browned and cooked through, about 6 to 8 minutes; drain any excess fat on paper towels. Scatter the cooked sausage over the croissant pieces, then sprinkle 1 cup shredded cheddar evenly across the pan so each bite will have pockets of melted cheese. Mix the custard: In a large bowl, whisk together 6 large eggs, 2 cups whole milk, 1 teaspoon salt, 1/2 teaspoon black pepper, 1/2 teaspoon garlic powder, and 1/2 teaspoon onion powder until fully combined. Whisk vigorously for 30 seconds to incorporate air for a lighter custard. Combine and press: Pour the egg mixture evenly over the croissant, sausage, and cheese layers. Use a spatula to gently press down on the croissant pieces so they begin to absorb the custard; this helps ensure an even soak and prevents dry pockets. Cover the dish tightly with foil. Refrigerate overnight: Place the covered dish in the refrigerator for at least 6 hours or overnight. Cooling allows the croissants to fully hydrate and the flavors to meld. For best texture, do not let it sit longer than 24 hours. Bake in the morning: Preheat the oven to 350 degrees Fahrenheit (175 degrees Celsius). Uncover the casserole and bake on the middle rack for 40 to 45 minutes, until the top is golden brown and the center is set; an inserted knife should come out mostly clean. Let rest 10 minutes before serving, then garnish with fresh parsley if desired.

Storage Tips

Store leftovers in an airtight container in the refrigerator for up to four days. For longer storage, cut into individual portions, wrap tightly in plastic wrap and foil, and freeze for up to three months. To reheat from frozen, thaw overnight in the refrigerator, then warm in a preheated 350 degree Fahrenheit oven for 15 to 25 minutes depending on portion size. Use shallow, oven-safe containers for faster reheating and to preserve crisp edges. If microwaving, cover loosely to retain moisture and avoid rubbery eggs.

Ingredient Substitutions

Swap the pork sausage for cooked turkey sausage or plant-based crumbles if you prefer. Replace cheddar with Swiss, Monterey Jack, or mozzarella for different melt characteristics; use about 1 cup shredded regardless of type. For a richer custard, use half-and-half in place of milk at a one-for-one ratio. If croissants are not available, use brioche, challah, or even cubed day-old white bread, though the pastry quality will be slightly different. Reduce salt slightly if using pre-seasoned sausage.

Serving Suggestions

Serve slices warm with a simple green salad dressed in lemon vinaigrette or with roasted tomatoes for brightness. Offer condiments like ketchup, hot sauce, or a dollop of sour cream for varied preferences. For brunch buffets, provide small tongs and garnish with chopped parsley or chives. Pair with fresh fruit, coffee, or a light sparkling beverage to balance the richness. Individual portions reheat nicely for weekday breakfasts with a side of plain yogurt.

Cultural Background

This dish is rooted in the classic technique of savory bread puddings and strata, which have European origins as a way to use stale bread. The use of croissants adds a French-influenced pastry element that elevates a humble strata into a more indulgent morning centerpiece. Variations of custardy bakes appear across many cuisines as a clever way to refresh leftovers while creating celebratory dishes for holidays and family gatherings.

Seasonal Adaptations

Adapt this dish for spring by adding blanched asparagus tips and fresh peas; in summer include roasted bell peppers and basil. In fall, fold in sautéed mushrooms, caramelized onions, or a handful of grated Gruyère for earthier flavors. For winter holidays, mix in chopped cooked ham and a pinch of nutmeg in the custard for warmth. Adjust baking times slightly when adding moist vegetables to avoid a watery custard.

Meal Prep Tips

Assemble the casserole the night before in a disposable or oven-safe 9 by 13-inch pan if you plan to transport it. Label with the date and bake the following morning. For portioned meal prep, divide into individual ramekins, cover, and refrigerate; bake for 20 to 25 minutes until set. Use silicone muffin tins to make single-serve cups that can be frozen and reheated for quick breakfasts. Keep garnishes separate until serving to maintain fresh color and texture.

This overnight croissant breakfast casserole is one of those recipes that turns simple ingredients into an effortless celebration. It invites creativity, reduces waste, and always earns compliments at the table. Make it your own by experimenting with cheeses, proteins, and vegetables, and enjoy the ease of waking up to a fully assembled dish that bakes into something comfortingly special.