Combine 1/2 cup spaghetti sauce, ground beef, bread crumbs, onion, egg and pepper; mix well. In 13 x 9-inch baking dish, pat ground beef firmly into bottom of dish. Bake at 400 degrees for 10 minutes; spoon off fat. Prepare muffin mix as per package instructions; stir in chopped chilies. On beef mixture, spread remaining sauce; sprinkle with cheese. Spread corn muffin mix over all and bake 15 minutes more to golden brown.