This overnight croissant breakfast casserole started as a way to use up day-old pastries and has since become my go-to brunch centerpiece for busy mornings and holiday gatherings. I discovered the combination on a sleepy Sunday when a stack of croissants threatened to go stale and a pound of sausage needed using. The result—rich custard soaked into buttery layers of croissant, pockets of savory sausage, and gooey cheddar—felt like a crossroads between French pastry and classic American comfort food. It’s the kind of dish that fills the kitchen with warm, inviting aromas and gets everyone to the table early.

I love how forgiving and flexible this dish is: tear the croissants roughly, stir in whatever cooked protein or veggies you have on hand, whisk up a simple egg-milk custard, and refrigerate overnight. In the morning you simply bake until the top is golden and the center is set. Texturally it’s remarkable—crispy edges where the croissant pokes above the custard, a tender, bread-pudding-like interior, and melty cheese pockets that thread everything together. Over the years I’ve adapted this for crowds, weeknight meal prep, and holiday brunches; every time it disappears fast and usually inspires requests for the recipe.

Ingredients

• Croissants (5 large): Day-old croissants are ideal because they absorb the custard without turning to mush. Look for high-butter varieties or bakery-style croissants; store-bought works fine. Tear into large chunks for pockets of pastry that remain slightly crisp around the edges.
• Ground sausage (1 lb): Use classic pork breakfast sausage for a rich, savory base. Cook it until browned and drain well to avoid a greasy bake. Swap to turkey or a plant-based sausage for lighter or vegetarian options—season to taste if your substitute is mild.
• Cheddar cheese (1 cup shredded): Sharp cheddar gives a bright, tangy contrast to the buttery croissants. Pre-shredded cheddar is convenient, but freshly shredded melts more smoothly—choose a full-flavored variety if you want pronounced cheese notes.
• Eggs (6 large): Provide structure to the custard—use large eggs straight from the fridge. Whisk thoroughly so the custard is homogeneous and sets uniformly while baking.
• Whole milk (2 cups): Produces a rich, velvety custard; you can substitute half-and-half for an even creamier result, or lower-fat milk if you prefer a lighter finish.
• Seasonings: 1 teaspoon salt, 1/2 teaspoon black pepper, 1/2 teaspoon garlic powder, and 1/2 teaspoon onion powder—simple aromatics that boost flavor without overpowering the buttery pastry.
• Garnish: Fresh parsley, chopped (optional) to add brightness and color at serving.

Instructions

Prepare the Base: Preheat nothing yet—start by greasing a 9×13-inch baking dish with butter or nonstick spray. Tear 5 large croissants into large chunks (about 2–3 inch pieces) and layer them evenly across the dish so the custard can reach all the pastry. Distribute 1 lb of cooked, drained sausage and 1 cup shredded cheddar over the croissant pieces. Even distribution prevents dense or dry pockets when baked. Make the Egg Mixture: In a large bowl, whisk 6 large eggs with 2 cups whole milk until smooth and slightly frothy. Whisk in 1 teaspoon salt, 1/2 teaspoon black pepper, 1/2 teaspoon garlic powder, and 1/2 teaspoon onion powder. Pour the custard evenly over the croissant-sausage-cheese layers. Use a rubber spatula to press the croissants down gently so they absorb the liquid—pressing is crucial for uniform soaking and avoids dry centers. Refrigerate Overnight: Cover the dish tightly with foil and refrigerate for at least 6 hours or overnight. During this period the croissants will soften and absorb the custard, setting up a bread-pudding-like texture. Overnight chilling also melds flavors—seasonings and sausage juices steep into the pastry. Bake in the Morning: Preheat the oven to 350°F (175°C). Remove the foil and place the dish on the middle rack. Bake for 40–45 minutes until the top is golden brown and the center is set—test by inserting a knife into the center; it should come out mostly clean with a few moist crumbs, not runny custard. If the top browns too quickly, tent loosely with foil for the last 10–15 minutes. Rest and Serve: Let the casserole rest 10 minutes before slicing; this helps the custard finish setting and makes cleaner portions. Sprinkle chopped parsley over the top for color, slice into squares, and serve warm. Leftovers keep well refrigerated and reheat beautifully.

Storage Tips

Store cooled pieces in an airtight container in the refrigerator for up to 4 days. For longer storage, wrap individual portions tightly in plastic wrap and place in a freezer bag; keep for up to 3 months. Reheat frozen slices directly from the freezer at 350°F for 18–22 minutes, or thaw overnight in the fridge and reheat for 10–12 minutes. Use oven or toaster oven reheating to preserve the crust; microwaving is faster but yields a softer texture. Look for visual indicators of freshness—no off-odors, no freezer burn—before reheating.

Ingredient Substitutions

If you’re avoiding pork, swap the sausage for cooked ground turkey or chicken; to maintain seasoning, add 1/4 teaspoon additional salt and 1/4 teaspoon smoked paprika to compensate for milder flavors. For dairy-free versions, use a full-fat plant-based milk and dairy-free cheese, although the custard will be slightly less rich. Gluten-free croissants are an option if you can source them—expect a different crumb but similar soaking behavior. For extra vegetables, add 1 to 1 1/2 cups of sautéed spinach, mushrooms, or diced bell peppers, pre-cooked to remove excess moisture so the custard remains stable.

Serving Suggestions

Serve this with a crisp green salad for brunch balance, roasted potatoes or a fresh fruit platter for sweetness contrast. Garnish with chopped parsley or chives and a drizzle of hot sauce for those who like heat. On holiday mornings, present it alongside smoked salmon, sliced tomatoes, and a bowl of mixed berries. For a more formal brunch, cut into neat squares and serve on warmed plates with a side of hollandaise or a mustard-yogurt dipping sauce for an upscale twist.

Cultural Background

This dish blends ideas from bread pudding and strata—savory, layered custard bakes rooted in European and American home cooking. Stratas became popular in mid-20th century America as a way to feed crowds with simple pantry ingredients. Using croissants nods to French pastry traditions, combining flakiness and butter richness with the comforting custard of American strata. Over time, cooks have adapted the concept with regional fillings: smoked salmon and dill in Nordic-inspired versions, chorizo and peppers in southwestern adaptations, showing the recipe’s flexibility.

Seasonal Adaptations

Spring: add blanched asparagus tips and fresh herbs like tarragon for brightness. Summer: fold in roasted peppers and fresh tomatoes, swap cheddar for a lighter Monterey Jack. Autumn: incorporate sautéed mushrooms and caramelized onions with Gruyère for deeper flavors. Winter: choose hearty additions like roasted Brussels sprouts and a smoked sausage, and use half-and-half for richer custard that feels more indulgent on cold mornings. Adjust baking times slightly for added moisture from vegetables.

Meal Prep Tips

Assemble the casserole the night before for weekday breakfasts—cover and refrigerate, then bake in the morning while you shower or prepare coffee. If you’re prepping multiple portions, cut into individual squares before freezing to simplify thawing and reheating. Label and date frozen portions, and consider making a double batch for busy weeks. When transporting for potlucks, bake until just set, cool completely, then warm in a covered slow cooker on low for easy serving.

This casserole has earned a permanent slot in my brunch rotation because it’s reliably delicious, forgiving, and endlessly adaptable. Whether you’re feeding a crowd or prepping breakfasts for the week, it delivers comfort, texture, and convenience in one satisfying dish. Give it a try—then make it your own by swapping fillings and cheeses to match your pantry and taste.