Croque Monsieur Casserole (Printable Version)

Comforting French casserole featuring buttery bread, ham, Gruyère cheese, and creamy béchamel sauce.

# What You’ll Need:

→ Bread & Dairy

01 - 12 slices white sandwich bread, crusts removed
02 - 3 tablespoons unsalted butter, softened
03 - 1.5 cups Gruyère cheese, grated
04 - 1 cup whole milk
05 - 0.5 cup heavy cream
06 - 3 large eggs

→ Meats

07 - 8 slices cooked ham, approximately 7 ounces

→ Béchamel Sauce

08 - 2 tablespoons unsalted butter
09 - 2 tablespoons all-purpose flour
10 - 1.25 cups whole milk
11 - 0.25 teaspoon ground nutmeg
12 - Salt and black pepper to taste

# Step-by-Step Guide:

01 - Preheat oven to 375°F. Lightly butter a 9x13-inch baking dish.
02 - In a medium saucepan, melt 2 tablespoons butter over medium heat. Whisk in flour and cook for 1 minute, stirring constantly. Gradually add 1.25 cups milk while whisking continuously until thickened and smooth, approximately 3 to 4 minutes. Season with nutmeg, salt, and pepper. Remove from heat.
03 - Spread butter on one side of each bread slice.
04 - Arrange half the bread slices, buttered side down, in the prepared baking dish.
05 - Top bread with half the ham slices and half the Gruyère cheese.
06 - Repeat with remaining bread slices, buttered side down, followed by remaining ham and cheese.
07 - In a mixing bowl, whisk together eggs, 1 cup milk, heavy cream, and a pinch of salt until well combined.
08 - Pour custard mixture evenly over the casserole, pressing gently to allow bread to absorb liquid.
09 - Pour prepared béchamel sauce over the top and spread evenly with a spatula.
10 - Bake uncovered for 35 to 40 minutes until puffed, golden brown, and bubbling at edges. Allow to rest for 10 minutes before serving.

# Additional Tips::

01 -
  • It turns the fussy bistro sandwich into a dish you can assemble ahead and bake when guests arrive.
  • Every bite has that perfect balance of creamy béchamel, nutty Gruyère, and salty ham without any last-minute stress.
  • Leftovers reheat beautifully, and honestly taste even better the next morning with coffee.
02 -
  • Don't skip the resting time after baking or the custard will run everywhere when you try to serve it, and you'll lose that perfect layered look.
  • Press the bread gently into the custard before baking so every slice soaks up the liquid, otherwise you'll end up with dry patches that taste like plain toast.
  • Use day-old bread if you have it because fresh bread can turn too soft and almost dissolve into the custard instead of holding its shape.
03 -
  • Grate your own Gruyère instead of buying pre-shredded because the anti-caking agents in bagged cheese can make the sauce grainy and prevent it from melting smoothly.
  • If your béchamel gets lumpy, pour it through a fine-mesh strainer before adding it to the casserole and no one will ever know.
  • Let the casserole rest on the counter for 10 full minutes after baking so the custard firms up and you get clean, Instagram-worthy slices instead of a sloppy mess.
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