Mix bread crumbs with meat. Combine remaining-ingredients. Blend into meat-bread mixture. Pack lightly into a 9-inch casserole and bake in a moderate oven (325 degrees F) 30 minutes.
To make topping: beat egg whites until foamy; add cream tartar; beat until very stiff. Fold in mustard gently. Swirl on hot meat; return to oven;bake 20 to 25 minutes longer or until tipped with brown. Makes 6 to 8 servings.
Friendly warning: Because French’s Mustard is made with rare spices, specially-grown mustard seeds and finest vinegar, it has a special flavor, texture and color all its own. Don’t expect the best results from this recipe with any other mustard.