Buvette's Croque Monsieur

Preheat oven to 400 degrees.

Make the bechamel: Melt butter in a saucepan over medium heat. Add flour, and cook, stirring with a wooden spoon for 2 minutes. Increase heat to medium-high, and slowly add hot milk. Cook, whisking constantly, until thickened, 5 to 6 minutes. Remove pan from heat, and add salt, pepper, nutmeg, and 1/2 cup Gruyere.

Lightly brush 4 slices bread with mustard. Add 1 slice baked ham to each, and sprinkle each with 2 tablespoons Gruyere. Top with 4 more slices toasted bread. Slather tops with bechamel, and sprinkle with remaining Gruyere and 1/4 teaspoon herbes de Provence.

Bake sandwiches until topping is lightly browned, about 12 minutes. Serve hot with cornichons.