Ingredients

makes 4

　　2 tablespoons unsalted butter, plus more for spreading, room temperature

　　2 tablespoons all-purpose flour

　　1 cup milk

　　1/2 teaspoon coarse salt

　　Pinch of freshly ground nutmeg

　　Pinch of cayenne pepper

　　Pinch of freshly ground black pepper

　　8 slices rustic French or firm white sandwich bread

　　1/4 cup Dijon or whole-grain mustard

　　1/2 pound cooked ham, thinly sliced

　　1/3 pound Gruyère cheese, thinly sliced, plus 1 cup freshly grated (about 2 ounces)

　　

Step 1

Melt the butter in a small saucepan over medium heat until just starting to bubble. Add the flour, and cook, whisking constantly, until smooth but not browned, about 3 minutes.

　　

Step 2

Whisking constantly, slowly add the milk; continue cooking while whisking until mixture has thickened, about 3 minutes more. Remove from heat, and add salt, nutmeg, cayenne, and black pepper. Transfer to a bowl; place plastic wrap directly on surface of sauce, and set aside.

　　

Step 3

Heat the broiler. Heat a griddle or large cast-iron skillet over medium-low heat. Smear one side of bread slices with mustard. Top 4 slices with a layer each of ham and cheese; cover with the remaining 4 bread slices, pressing gently to adhere. Generously butter the outer sides, spreading all the way to the edges.

　　

Step 4

Place the sandwiches on the griddle or in the skillet. Cook until the bread is golden brown and cheese has melted, 3 to 4 minutes a side. Transfer to a work surface; divide béchamel sauce evenly over tops, spreading to edges; sprinkle with grated cheese.

　　

Step 5

Transfer to the broiler, and cook until the cheese topping is melted and golden, 2 to 3 minutes. Serve immediately.

　　Reprinted with permission from The Martha Stewart Living Cookbook: The New Classics by Martha Stewart Living Magazine, copyright © 2007. Published by Clarkson Potter, a division of The Crown Publishing Group.Buy the full book from Amazon.