Cheeseburger Bisquit Pie

1 (12oz) can Pillsbury® Big Country® Buttermilk Bisquits
1 lb. lean ground beef
¼ cup chopped onion
1/3 cup ketchup
3 TBS mustard
¼ tsp salt
¼ tsp pepper
7 slices American cheese

Heat oven to 400°F and grease a 9-inch pie pan. Separate dough into 10 bisquits. Press 6 bisquits over bottom and up sides of pie pan to form crust. Cut remaining 4 biscuits into quarters and set aside. In large skillet, brown ground beef and onion until thoroughly cooked, drain. Add ketchup, mustard, salt and pepper. Heat until bubbly. Spoon into biscuit-lined pan. Arrange cheese slices on top of beef mixture. Place biscuit quarters, point side down around edge of pie pan. Bake at 400°F for 15 to 17 minutes or until biscuits are golden brown. Serves 6.