Serves 6 to 8.
Preheat oven to 400ºF. Press pie crust into bottom up sides of ungreased pie pan; flute edge of pastry. Prick base of piecrust with fork. Bake 10-12 minutes or until lightly browned. Cool completely.
In medium skillet, brown beef with onion, garlic and black pepper over medium heat 8-10 minutes or until beef is no longer pink; drain well. Stir in ketchup and, if desired, mustard; mix well. Arrange cheese slices to form a single layer covering bottom and sides of cooled crust; add beef mixture. Tint 2 cups of the potatoes medium rose; spread over top of “pie”. Place remaining potatoes into decorating bag fitted with Tip 1M; pipe rosettes around edge of pie. Return pie to oven to warm, about 5-10 minutes.