Preheat oven to 400°F.

Place a slice of ham and a slice of cheese between two pieces of bread; repeat this step on the same sandwich to make a triple-decker sandwich.

Repeat to make 4 sandwiches in all. Arrange the sandwiches in a baking dish.

Make the béchamel: Combine the flour, milk, butter, salt, and pepper in a saucepan. Heat over low heat, stirring constantly with a wire whisk, until the flour has completely dissolved.

Pour the béchamel (white sauce) mixture over the sandwiches and top with the grated Swiss cheese.

Bake for 15 minutes, or until the cheese is melted and crusty.

Serve on 4 plates. Cut sandwiches into halves or quarters.