1/4teaspoonfine salt, reduce slightly if using salted butter
1/8teaspoonfreshly ground black pepper
Sandwiches:
4slicesBrioche, Challah or Pain de Mie bread, sliced 1/2-inch thick
1teaspoonDijon mustard
2slicesham, about 1/4-1/2-inch thick
2/3cupGruyère or Comté cheese, grated
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Instructions
Make the Béchamel (can be done ahead):
In a small saucepan, heat the milk over medium heat until hot, but not yet simmering at all. (Watch carefully, as milk can boil up and and over really quickly). Remove from heat and set aside.
In a medium saucepan, melt the butter over medium heat. Add the flour and cook, stirring constantly, for about 1 - 1 1/2 minutes with a wooden spoon. Don't let the mixture brown. Slowly add the hot milk to the butter/flour mixture, whisking constantly, until smooth and thickened, about 2-3 minutes. Remove from heat and stir in the nutmeg, salt and pepper. If not using right away, transfer to a bowl, allow to cool slightly, then cover with plastic wrap and refrigerate. Béchamel will keep in the fridge for 4-5 days.
Assemble the sandwiches:
Preheat oven to 425F.
Using a toaster or the oven broiler, toast the bread slices until golden. Spread 2 slices of bread with a thin layer of Dijon mustard. Top with the ham slice. Top the each ham slice with about 1/4 cup of shredded cheese.
Tip: If you have made the Béchamel ahead and refrigerated, it will be quite a bit stiffer. Give it a good stir to loosen it up a bit, then just use it as it is, spreading it out, rather than spooning it. It will melt up just fine once it hits the oven.
Spread the remaining two slices of bread with some of the Béchamel, then place on top of the shredded cheese, Béchamel side down. Place assembled sandwiches on a baking sheet.
Spoon or spread a generous amount of Béchamel over-top of each of the sandwiches, spreading it around so that it covers the entire top, as any exposed bread on the top might scorch when under the broiler. (Don't skimp on the Béchamel on top. You want it to bubble up and fall over the edge a bit. Scatter the remaining shredded cheese over-top.
Place into preheated 425F oven and bake for 4 minutes, then switch the oven to BROIL and broil about 4 minutes more, or until the top of the sandwiches are bubbly and golden (you may need to move the baking sheet up a rack position, if it doesn't seem to be browning).
Remove from the oven. Serve warm with a dollop of raspberry jam. You can serve whole or cut in half diagonally. Depending on the size of the sandwich, 1/2 a sandwich may be a suitable serving size for many people.
Notes
Nutritional information is per sandwich, but as this sandwich is quite rich, 1/2 a sandwich would be a serving for most people. Be sure to read the information above this Recipe Card, for more tips on making this recipe. You'll also find Step-by-Step photos there, as well.