Classic Croque-Monsieur (French Grilled Ham & Cheese)

Make the Béchamel - Gather the ingredients.

Make the Béchamel - Heat milk in a small saucepan on the stove or in a glass measuring cup in the microwave until hot but not boiling.

Make the Béchamel - Meanwhile, melt butter in a saucepan or saucier over medium heat.

Make the Béchamel - Add flour to the pan with the butter-flour mixture and whisk until mixture is well blended. Cook, whisking constantly, for 2 minutes.

Make the Béchamel - Gradually whisk in hot milk. Cook over medium heat, whisking constantly, until sauce begins to boil and thicken, about 1 minute.

Make the Béchamel - Reduce heat to very low, and simmer, whisking frequently until sauce is smooth and thickened, about 5 minutes.

Make the Béchamel - Season with salt and pepper to taste and add a little nutmeg, if desired.

Make the Sandwich - Gather the ingredients. Position a rack 6 to 8 inches from the broiler and set the oven to broil.

Make the Sandwich - Trim the crusts off of the bread, making the slices as square as possible.

Make the Sandwich - Spread both slices of bread with butter.

Make the Sandwich - Flip bread over and spread them lightly with Dijon mustard.

Make the Sandwich - In a bowl, combine the cheese and half of the béchamel sauce, and mix until the cheese is fully coated.

Make the Sandwich - Spread half the cheese mixture evenly onto one slice of bread (on the mustard side, not the butter side). Lay the sliced ham atop the other slice.

Make the Sandwich - Press both halves of the sandwich together.

Make the Sandwich - Spray a bit of cooking spray onto the surface of a nonstick pan. Heat the pan over medium heat until the oil is hot and glistening but not quite smoking.

Make the Sandwich - Place the sandwich into the pan and cook for about 2 minutes, or until the bottom of the bread is a nice shade of golden-brown.

Make the Sandwich - Use a nonstick spatula to flip the croque-monsieur over. Lower the heat a bit and cover the pan. Cook for another minute or two, or until the second slice of bread is also golden brown, and the cheese inside the croque-monsieur is fully melted.

Make the Sandwich - Transfer the sandwich to a cutting board. Top with the remaining cheese mixture, then spoon the other half of the béchamel over the top.

Make the Sandwich - Place sandwich on a sheet tray and broil the sandwich, béchamel-side up, until the top of the sandwich is nicely browned, 1 to 3 minutes. Serve right away.