1In 12-inch nonstick skillet, cook beef and onion over medium heat about 5 minutes, stirring occasionally, until beef is brown; drain. Stir in beans and enchilada sauce.
2Place beef mixture in 3 1/2- to 4 1/2-quart slow cooker. In medium bowl, stir cornbread mix, milk, margarine and egg just until moistened (batter will be lumpy). Stir cheese and chiles into batter. Spoon over beef mixture in slow cooker.
3Cover and cook on low heat setting 5 to 6 hours or until toothpick inserted in center of cornbread comes out clean. Serve with sour cream and green onions.