
Overnight Croissant Breakfast Casserole is the kind of recipe that transforms an ordinary morning into something delicious and memorable. It is perfect for busy families or anyone hosting brunch. The scent of baking croissants, sausage, and cheddar will win over even sleepyheads in the house.
I first made this for a Christmas morning, and it has become a special tradition ever since. The best part is waking up to a ready-to-bake breakfast while everyone unwraps gifts.
Ingredients
- Croissants: large and fluffy these add richness and soak up the custard for a soft yet crisp top try to use fresh bakery croissants if possible
- Breakfast sausage: classic pork sausage adds a savory bite look for one with good seasoning and not too much fat
- Shredded cheddar cheese: brings a gooey melt and sharp flavor choose extra sharp for bolder taste
- Eggs: large eggs provide structure and richness make sure they are fresh for the fluffiest texture
- Milk: whole milk makes the custard creamy you can use half and half for extra richness if desired
- Dry mustard: gives a tiny bit of warmth and depth do not skip this as it makes a difference
- Salt: enhances all the flavors use kosher salt for best control
- Black pepper: fresh cracked wakes up the whole dish use more or less to taste
Step by Step Instructions
- Prepare the Baking Dish:
- Grease a large nine by thirteen inch baking dish making sure to get the corners Cover the bottom evenly with croissant pieces so every bite will have that golden base
- Add Sausage and Cheese:
- Scatter the cooked crumbled sausage over the croissants then sprinkle the shredded cheddar evenly all over This layering ensures you get sausage and cheese in every portion
- Make the Egg Mixture:
- In a large bowl whisk together eggs milk dry mustard salt and pepper until the mixture is completely smooth and streak free This custard is what binds the casserole and gives it a souffle like quality
- Assemble the Casserole:
- Gently pour the egg mixture over the croissant sausage and cheese layers Press down with a spatula just enough so the croissant pieces start soaking up the liquid but do not crush them
- Refrigerate:
- Cover tightly with plastic wrap and refrigerate overnight or at least two hours This long soaking helps the custard absorb and gives the casserole a lush texture
- Bake:
- Preheat your oven to three hundred fifty degrees Fahrenheit Remove the casserole from the fridge and let it rest on the counter while the oven heats Bake uncovered for about forty five minutes You want the top golden brown and the center set with a bit of a jiggle
- Serve:
- Let the casserole cool for a few minutes before cutting into squares Serving warm brings out the cheese and sausage flavors the best

One of my favorite parts of this casserole is the way the edges of the croissants crisp up in the oven while the inside stays tender each bite feels luxurious My kids still talk about the first time we ate this on a snowy morning with the windows steamed from baking
Storage Tips
Store leftovers tightly covered in the refrigerator for up to three days Reheat slices in the oven or microwave for best results If you want to freeze assemble but do not bake double wrap in foil and freeze for up to two months Thaw overnight in the fridge before cooking as usual
Ingredient Substitutions
If you need a vegetarian option swap the sausage for sautéed mushrooms spinach or bell peppers You can also try turkey or chicken sausage for a lighter version For the cheese mozzarella Swiss or gruyere all work well and each brings a unique twist
Serving Suggestions
This casserole pairs beautifully with a bowl of fresh mixed berries or a crisp green salad For heartier appetites serve with roasted potatoes or a fruit salad Add fresh orange juice or hot coffee to round out your brunch spread

Cultural Glimpse
Breakfast casseroles like this have deep roots in American brunch culture especially in the Midwest and South They combine convenience with comfort making them favorites for holiday mornings or Sunday gatherings I love that every family puts their own spin on this dish
Frequently Asked Questions
- → Can I use store-bought croissants?
Absolutely, store-bought croissants work well. Just ensure they’re fresh and of good quality for best results.
- → Are there alternatives to sausage?
Yes, you can use cooked bacon, turkey sausage, or plant-based sausage. For a vegetarian option, try sautéed vegetables like mushrooms or spinach.
- → Can this dish be frozen before baking?
Yes, assemble and tightly cover the dish, then freeze for up to two months. Thaw overnight in the refrigerator before baking as usual.
- → How should leftovers be stored?
Place any leftover portions in an airtight container and refrigerate for up to three days. Reheat in the oven or microwave as needed.
- → Can I swap out the cheese?
Certainly! Swiss, Gruyère, or mozzarella are tasty alternatives to cheddar and provide a different flavor profile.