Wash and clean scallops, then drain. Grease the empty shells with butter and line with bread crumbs, shaking the excess crumbs out. Place 2 or 3 scallops in each shell.

Meanwhile, make an ordinary white sauce and add 2 cups grated cheese, 1/4 teaspoon dry mustard, salt and pepper. Pour over the scallops and sprinkle some paprika over. Bake in a moderate oven until cooked.