Heat oven to 375°F. Cut thin slice from stem end of each bell pepper to remove top. Remove seeds and membranes; rinse peppers. Reserve tops. If necessary, cut thin slice from bottom of peppers so they stand up straight. Using small sharp knife, cut out small eyes, nose and teeth from each pepper to look like jack-o’-lantern.
Cook rice in microwave as directed on package. Meanwhile, in 12-inch skillet, cook beef and chopped vegetables over medium-high heat 5 to 7 minutes, stirring occasionally, until beef is thoroughly cooked; drain. Stir in 1/2 cup of the tomato sauce, the ground pepper and cooked rice. Stir in cheese.
Stuff peppers with beef mixture. Pour remaining tomato sauce in ungreased 11x7-inch (2-quart) glass baking dish. Stand peppers upright in dish. Replace pepper tops.
Cover tightly with foil. Bake 45 minutes. Uncover; bake about 15 minutes longer or until peppers are tender.