Overnight Croissant Breakfast Casserole Recipe tastes like a buttery, cheesy strata with crisp edges, custardy middles, and savory bites of ham and herbs. It suits busy hosts, holiday brunch lovers, and sleepy parents, and it takes about 10 hours total with the overnight rest. I tested it after a 5 a.m. kid alarm and felt very smug when the croissants puffed like little golden pillows.
Overnight Croissant Breakfast Casserole Recipe
This Overnight Croissant Breakfast Casserole Recipe uses tear-and-toss croissants, a quick whisked custard, and a fridge rest that does all the work while you sleep. Skip fussy layering and use store-bought croissants that soak like champs. You wake up, bake, and bask in buttery aroma therapy.
Ingredients You Need
- 6 to 8 large croissants, preferably day-old bakery style (stale croissants absorb better; if fresh, toast halves at 300 F for 8 minutes)
- 8 large eggs
- 2 cups whole milk or 1.5 cups whole milk + 0.5 cup half-and-half (richer custard with half-and-half)
- 1.5 cups shredded Gruyère or Swiss (sharp cheddar also works; pre-shredded saves time)
- 1 cup diced ham (thick-cut deli ham, or use cooked bacon or sausage; for vegetarian, use sautéed mushrooms)
- 1 small yellow onion or 2 shallots, finely chopped
- 1 red bell pepper, diced (optional but tasty)
- 2 tablespoons Dijon mustard (maille or your favorite brand)
- 1 teaspoon kosher salt (reduce to 3/4 teaspoon if your meat runs salty)
- 1/2 teaspoon black pepper
- 1/2 teaspoon garlic powder or 1 small clove garlic, minced
- 1 tablespoon fresh thyme or 2 tablespoons chopped chives (or 1 teaspoon dried Italian seasoning)
- 1/4 teaspoon ground nutmeg (optional but classic with dairy)
- 2 tablespoons unsalted butter, for the dish
- Hot sauce or chili flakes for serving (optional)
Equipment:
- 9×13 inch baking dish
- Large mixing bowl and whisk
- Skillet for vegetables
- Cutting board and knife
- Foil and plastic wrap
Pantry shortcuts and swaps:
- Use pre-shredded cheese to save time.
- Grab a bag of mini croissants and use about 14 to 16.
- Stir in 1 cup frozen spinach, thawed and well squeezed, instead of bell pepper.
How to Make Overnight Croissant Breakfast Casserole
- Prep: 20 minutes
- Chill: 8 to 24 hours
- Cook: 40 to 45 minutes
- Rest: 10 minutes
- Total: about 9 hours 10 minutes
- Butter the dish. Tear croissants into big bite-size chunks and scatter them evenly in the dish.
- Sauté onion and bell pepper in a little olive oil over medium heat until soft and fragrant, about 5 minutes. Cool for a minute so the heat does not scramble the eggs later.
- Whisk eggs, milk, half-and-half, Dijon, salt, pepper, garlic, thyme, and nutmeg in a large bowl until smooth.
- Add the ham, sautéed vegetables, and 1 cup of the cheese to the egg mixture. Stir to distribute everything.
- Pour the custard over the croissants. Press the top croissant pieces down gently so they sip up the custard.
- Sprinkle the remaining 1/2 cup cheese over the top. Cover tightly with plastic wrap.
- Refrigerate for at least 8 hours and up to 24 hours. The croissants will soak and swell with custard.
- Heat the oven to 350 F. Uncover the dish and tent loosely with foil to prevent over-browning.
- Bake for 25 minutes with the foil on. Remove the foil and bake 15 to 20 minutes more, until the center feels set and the top looks golden.
- Check doneness by poking the center; it should spring back, and a knife should come out mostly clean. If the middle looks soupy, bake 5 to 10 minutes more.
- Rest the casserole for 10 minutes on a rack. The custard will finish setting, and slices will hold their shape.
- Slice and serve hot. Add chives and a dash of hot sauce if you like a kick.
Tips
- Use day-old croissants for best soak and texture. If you only have fresh, toast them briefly to dry the surface.
- Tear, don’t slice. Rough edges hold custard and give better crunch on top.
- Season wisely. Salt the custard lightly if you use salty ham or bacon.
- Avoid soggy centers. Press down the croissants after pouring the custard so the top layers drink it in.
- Control browning. Tent with foil early, then remove to finish color and keep the top from scorching.
- Don’t rush the rest. Let it sit 10 minutes after baking so slices cut clean.
- Keep the ratio balanced. Use enough croissant to soak up eggs; overflowing custard leads to puddles.
Variations I’ve Tried
- Spinach, mushroom, and Gruyère with a pinch of nutmeg for a meatless brunch.
- Bacon, sharp cheddar, and scallions with a light drizzle of maple at the table.
- Sausage, roasted poblano, pepper jack, and cilantro for a mild heat.
- Smoked salmon, dill, capers, and Swiss with a squeeze of lemon after baking.
- Sun-dried tomatoes, basil, and mozzarella with a few olives for a briny pop.
How to Serve Overnight Croissant Breakfast Casserole
Serve this croissant breakfast casserole hot with fresh chives and a simple arugula salad with lemon and olive oil. Add a bowl of berries or citrus to cut the richness. Pour coffee for weekdays or pour mimosas for brunch, no judgment. A little hot sauce or salsa on the side makes each slice sing.
Make-Ahead
Assemble the casserole up to 24 hours in advance and chill. Bake straight from the fridge and add 5 minutes if the center needs extra time.
Store leftovers covered in the fridge for 3 to 4 days. Reheat slices in a 325 F oven for 12 to 15 minutes, covered with foil, until hot. For a quick option, microwave a slice for 60 to 90 seconds, then crisp the top under the broiler for 1 to 2 minutes.
Freeze unbaked: wrap the assembled dish tightly and freeze for up to 2 months. Thaw in the fridge for 24 hours, then bake as directed, adding 10 to 15 minutes. Freeze baked leftovers in portions for up to 2 months and reheat at 325 F for 20 minutes.
Nutrition Information
Per serving, about 12 servings: 380 calories; 24 g fat; 23 g carbs; 18 g protein; 1 g fiber; 720 mg sodium. Numbers are estimates and vary by brand, croissant size, and add-ins.
Overnight Croissant Breakfast Casserole
Ingredients
Instructions
- Grease a 9x13 inch baking dish. Tear croissants into pieces and scatter evenly in the dish.
- Sprinkle shredded cheese, ham, bell pepper, and green onions over the croissant pieces.
- In a large bowl, whisk together eggs, milk, heavy cream, salt, and black pepper.
- Pour egg mixture evenly over the croissants and cheese.
- Cover the dish with plastic wrap and refrigerate overnight.
- In the morning, preheat oven to 350°F (175°C). Remove casserole from refrigerator while oven heats.
- Bake uncovered for 35-40 minutes, or until the casserole is puffed and golden and center is set.
- Remove from oven, let cool for a few minutes, then cut into slices and serve warm.