Go Back
A finished croque monsieur casserole in a white baking dish with a spoon resting inside.
Print Recipe
4.55 / 11 votes

Croque Monsieur Casserole

Croque monsieur—that perennial French classic—is the little black dress of the bistro set. Here we've given it a string of pearls, if you will, by making it a breakfast bake and using croissants. This is insanely rich, so a small piece goes a long way. (Or in our house, a not-so-long way.)
Prep Time15 minutes
Cook Time1 hour
Chill8 hours
Total Time9 hours 15 minutes
Course: Breakfast
Cuisine: French
Servings: 10 servings
Calories: 556

Equipment

  • 9-by-13-inch (23-by-33-cm) casserole dish

Ingredients

For the croque monsieur casserole

  • Butter, for the dish
  • 7 large croissants, (about 1 pound | 500 g)
  • Your favorite Dijon mustard
  • 14 slices deli ham, (about 8 ounces | 230 g)
  • 8 ounces Gruyère, Emmenthaler, Jarlsburg, or Swiss cheese, grated (about 2 cups)
  • 8 large eggs
  • 2 cups whole milk
  • Salt and freshly ground white pepper

For the béchamel sauce

  • 3 1/4 cups whole milk
  • 5 tablespoons (2 1/2 oz) unsalted butter
  • 5 tablespoons all-purpose flour
  • Pinch ground nutmeg
  • Salt and freshly ground black pepper
US - Metric

Instructions

Make the croque monsieur casserole

  • Butter a 9-by-13-inch (23-by-33-cm) casserole dish.
  • Slice the croissants lengthwise and spread with a bit of mustard.
    Halved croissants, spread with mustard, in preparation for making a croque monsieur casserole.
  • Tuck 2 slices of ham and about 1/4 cup cheese inside each croissant.
    Halved croissants topped with ham and shredded cheese for a croque monsieur casserole.
  • Cut each croissant into quarters, and fit the pieces in the dish. Turn them different ways, so some have frilly slices of ham showing.
    An assembled croque monsieur casserole prior to baking.
  • In a large bowl, whisk the eggs, then pour in the milk and whisk to combine. Season lightly with salt and pepper.
  • Evenly pour the egg mixture over the croissant pieces. Press down with your hands to make sure all the liquid is absorbed. Cover with plastic wrap and refrigerate overnight.
    Egg custard being poured over ham and cheese croissants for a croque monsieur casserole.

Make the béchamel sauce

  • In a medium saucepan over medium heat, warm the milk just until a skin begins to form on top, but the milk isn't boiling.
  • Meanwhile, in another medium saucepan over medium heat, melt the butter. Add the flour and stir constantly until the mixture bubbles, about 2 minutes.
  • Slowly pour the hot milk into the pan with the flour-butter mixture, whisking the whole time. Bring the mixture to a boil, then reduce to low and simmer until the béchamel thickens, 2 to 3 minutes more. Season with nutmeg, salt, and pepper.
  • Pour the sauce into a container, press plastic wrap against the surface to prevent a skin from forming, and let cool to room temperature. Refrigerate overnight.

Assemble the casserole

  • The next morning, remove the casserole and béchamel sauce from the refrigerator 30 minutes before baking. Crank the oven to 350°F (175°C).
  • Uncover the casserole and place it on a foil-lined rimmed baking sheet. Using a whisk, stir the béchamel to loosen it. Spread the sauce over the top, and sprinkle with the remaining cheese.
  • Bake the casserole until puffed and golden brown, 50 to 55 minutes.
    A cooked croque monsieur casserole.
  • Serve immediately.

Notes

Nutrition

Serving: 1portion | Calories: 556kcal | Carbohydrates: 31g | Protein: 25g | Fat: 37g | Saturated Fat: 20g | Trans Fat: 1g | Cholesterol: 252mg | Sodium: 727mg | Fiber: 1g | Sugar: 12g