Prepare and bake cornbread according to package directions. Meanwhile, in a large skillet, cook beef and onion over medium heat until meat is no longer pink; drain. Stir in the spaghetti sauce, corn, chiles and sloppy joe mix. Bring to a boil. Reduce heat; simmer, uncovered, for 10 minutes.
Sprinkle with cheese; cover and cook for 1 minute or until cheese is melted. Cut cornbread into six pieces; cut each piece in half. Top with sloppy joe mixture.