This croissant casserole recipe is the kind of dish that makes holiday brunches and weekend gatherings easy. Torn croissants soak up a rich custard of eggs, whole milk, and cream, then bake alongside crispy bacon and a generous layer of Gruyère and white cheddar until golden, puffed, and bubbly. Assemble it the night before, and it's ready to go into the oven the next morning.
Preheat the oven to 350 F. Combine the eggs, milk, cream, Dijon mustard, salt, and pepper in a large bowl. Whisk until smooth and set aside.
Grease a 13 x 9” casserole dish with butter. Scatter half of the crumbled bacon on the bottom of the pan. Spread torn croissants over the bacon in one even layer. Sprinkle the remaining bacon, Gruyère and cheddar over the croissants.
Pour the egg mixture evenly over the croissants. Gently press the croissants into the egg mixture to help soak them
Transfer the baking dish to the preheated oven and bake for 45 minutes, rotating the pan halfway. After 30 minutes, check the casserole for doneness. If the tops of the croissants are too brown, cover with foil and continue baking until the egg mixture is fully set and the top is golden and bubbly.
Remove from the oven and allow the casserole to cool for five minutes. Serve warm, sprinkled with chives, if desired.
