1. In a skillet over medium heat, cook beef, celery, onion and green pepper until the meat is no longer pink and vegetables are tender; drain. Stir in soup and mustard; mix well. Transfer to a greased 9-in. pie plate.
2. In a bowl, combine the baking mix and water until a soft dough forms. Turn onto a lightly floured surface; roll into a 9-in. circle. Place over meat mixture. Bake at 425 degrees F for 20 minutes or until golden brown. Cool for 5 minutes. Run a knife around edge to loosen biscuit; invert onto a serving platter. Arrange cheese slices in a pinwheel pattern on top. Garnish with green pepper rings if desired.

Yield: 6 servings