This overnight breakfast bake combines toasted, buttery croissants with sautéed spinach, mushrooms, eggs and freshly grated gruyère. It’s assembled the night before and baked the next morning for an effortless, impressive breakfast.
This is the kind of breakfast that will make holiday mornings feel extra special.
It’s toasty, buttery and deeply satisfying—one of the most delicious things you’ll ever try.
This croissant bake quickly became a favorite in our household. I first found the idea around the holidays and used fresh croissants from a local baker—perfect for this recipe.
I’ve tried many breakfast casseroles over the years—stratas, hashbrown bakes and farmer-style offerings—but this croissant version stands out. It’s rich and indulgent, and a little goes a long way, so it’s ideal for a crowd or a special morning.
The original inspiration comes from a New York Times recipe that includes sausage. I made that version and enjoyed it, but because I’m not a huge fan of sausage I adapted it to focus on vegetables instead. That change brought a fresher, lighter balance to the buttery croissants and cheese.
I use a classic combination of onions, mushrooms, garlic and baby spinach sautéed in butter. The vegetables pair beautifully with the crisp croissant pieces, melted gruyère and the rich egg custard. Fresh herbs and a touch of parmesan on top finish it off.
This is definitely decadent: very rich and hearty. It shines when served warm and straight from the oven, with a golden, bubbly top and tender custardy interior.
While you can add sausage or bacon if you prefer, the vegetable-forward version is what I make most often. It’s easy to customize—use extra greens, swap cheeses, or add cured meat if you like—so it’s a great way to use up ingredients from the fridge.
Tips for the best overnight croissant bake
- Toasting the croissants before assembling is essential. It adds caramelized flavor and texture and prevents the croissants from becoming too soggy.
- Use the full amount of egg, milk and cream—this custardy mixture is what makes the dish decadent and satisfying.
- This is a flexible clean-out-the-fridge recipe: add vegetables, greens, cooked sausage or bacon, different cheeses or fresh herbs to suit your tastes.
- Refrigerating overnight (at least 8 hours) yields the best texture and flavor. While a shorter 4–6 hour chill is acceptable, the bake develops better when left overnight.
Photography doesn’t always capture how delicious this is—trust the flavors. It’s buttery, crunchy, savory, cheesy and deeply satisfying.
Overnight Breakfast Bake
Overnight Croissant Breakfast Bake
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Ingredients
- 5 to 7 large croissants, sliced in half lengthwise
- 2 tablespoons unsalted butter
- 1 sweet onion, diced
- 2 garlic cloves, minced
- 10 ounces cremini mushrooms, chopped
- 8 ounces fresh baby spinach
- kosher salt and pepper
- 8 large eggs
- 2 ½ cups milk
- 1 cup heavy cream
- 8 ounces gruyère cheese, freshly grated
- fresh chopped parsley, for topping
- parmesan cheese, for topping
Instructions
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Preheat the oven to 450°F (230°C).
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Place the croissants cut-side up on a baking sheet and bake 5–8 minutes until toasty. Let cool slightly, then chop or tear into bite-sized pieces.
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Melt the butter in a large skillet over medium-low heat. Add the onion and garlic and cook about 5 minutes. Add the mushrooms and cook until they release their juices and soften, about 5 more minutes. Stir in the spinach until wilted. Season with a generous pinch of salt and pepper and remove from heat.
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Brush a 9×13-inch baking dish with melted butter. Combine the croissant pieces and the vegetable mixture in the dish and toss to mix evenly.
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In a large bowl, whisk together the eggs, milk, heavy cream and a big pinch of salt and pepper. Stir in 1 cup of the grated gruyère and any optional chopped fresh herbs.
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Pour the egg mixture over the croissant mixture, pressing down so the croissant pieces absorb the custard.
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Cover with plastic wrap and refrigerate for at least 8 hours or overnight.
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Preheat the oven to 350°F (175°C). Remove the dish from the fridge 30 minutes before baking to take the chill off.
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Remove plastic wrap and sprinkle the remaining grated gruyère over the top. Bake uncovered for about 45 minutes, until set and golden. Finish with grated parmesan and chopped parsley before serving.
Notes
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