- 3 tablespoons unsalted butter, plus more for baking sheet
- 1/4 cup all-purpose flour
- 2 cups milk
- 1 cup Gruyere or Swiss cheese, grated, plus 8 ounces, thinly sliced
- Coarse salt
- Freshly ground white pepper
- Freshly ground nutmeg
- 8 slices brioche, cut 1/2-inch thick, toasted
- 6 ounces baked ham, thinly sliced
Preheat oven to 450 degrees. Butter a baking sheet; set aside.
In a medium saucepan, melt butter over medium-high heat. Add flour, and cook until foaming, whisking constantly, for 3 minutes.
In another medium saucepan, heat milk over medium heat. Slowly add milk to butter-flour mixture, whisking to prevent lumps from forming. Bring mixture to a boil. Reduce heat to low, and cook 2 minutes more. Stir in 1/2 cup grated cheese, and season with salt, white pepper, nutmeg, and cayenne. Cook until thickened, 2 to 3 minutes. Remove from heat, transfer to a bowl, and set aside to cool.
Place 4 pieces of toast on a work surface and spread each piece with a 1/4 cup of sauce. Cover sauce with a slice of cheese, a slice of ham, and another slice of cheese. Top each sandwich with remaining 4 slices of toast. Spread each sandwich with 1/4 cup sauce and sprinkle evenly with remaining 1/2 cup grated cheese.
Place sandwiches on prepared baking sheet, and bake until heated through, about 5 minutes. Preheat broiler; transfer baking sheet to broiler and broil until golden brown and bubbly, 2 to 3 minutes. Serve immediately.