Heat oven to 400°F. Grease 9-inch pie pan with shortening. Separate dough into 10 biscuits. Press 6 biscuits in bottom and up side of pie pan to form crust. Cut remaining 4 biscuits into quarters; set aside.
In 10-inch skillet, cook ground beef and onion over medium heat, stirring frequently, until beef is thoroughly cooked; drain. Stir in ketchup, mustard, salt and pepper. Cook uncovered until bubbly. Spoon into biscuit-lined pan.
Arrange cheese slices on top of beef mixture. Place biscuit quarters, point side down, around edge of hot beef mixture.