HEAT oven to 350ºF.
BROWN meat with onions and peppers in large skillet. Stir in next 4 ingredients; cook and stir 3 min. or until heated through. Spoon into 13x9-inch baking dish.
PREPARE muffin batter as directed on package; stir in cheese. Spread over meat mixture.
BAKE 20 min. or until toothpick inserted in center of cornbread topping comes out clean. Cool slightly.