Brown ground beef; drain off fat. Add taco mix and 1/2 cup water. Cook over low heat about 15 minutes or until liquid has been absorbed. Spread in greased 9x13 inch baking pan. Spread beans over meat. Sprinkle with cheeses, then with chopped onion. Bake at 325F for 20 minutes or until hot. Makes 8 servings. Tip: If desired, serve or tortilla or corn chips and top with sour cream, avocado, chopped lettuce and tomatoes. Typed in MMformat by cjhartlin@msn. Com