Heat oven to 375°F. Spray large cookie sheet with cooking spray. In 10-inch skillet, cook beef, onion and bell pepper over medium-high heat until beef is thoroughly cooked; drain. Stir in ketchup, mustard, Worcestershire sauce, salt and pepper.
Separate dough into 8 biscuits. Place 2 1/2 inches apart on cookie sheet. With bottom of flat 2-inch diameter glass or fingers, press out each biscuit to 3 1/2-inch round with 1/4-inch rim around outside edge. In small bowl, beat egg yolk and water with fork. Brush over tops and sides of biscuits.
Spoon about 1/3 cup beef mixture into indentation in each biscuit. Sprinkle each biscuit with 1 tablespoon shredded cheese.
Bake 12 to 17 minutes or until biscuits are golden brown and cheese is melted.