1. In 4-quart saucepan over medium-high heat, cook beef and onion, stirring occasionally, until all pan juices evaporate and meat is browned. Stir in chili powder; cook 1 minute. Stir in tomatoes with their liquid, sugar, salt, and cracked pepper; over high heat, heat to boiling. Reduce heat to low; cover and simmer 30 minutes, stirring often. Stir in beans. Spoon mixture into 12" by 8" baking dish.
2. Preheat oven to 400°F. Prepare corn-muffin mix as label directs. With back of spoon, spread corn-muffin batter evenly over top of meat mixture in casserole. Bake casserole, uncovered, 15 to 20 minutes, until golden and toothpick inserted into corn bread comes out clean.