Taco Corn Bread Casserole

1 package (8 1/2 oz) corn bread/muffin mix
1 egg
1/3 cup milk
3 cups cooked taco seasoned meat
1 can black beans
1 cup (8 oz) sour cream, light
1 cup colby jack, cheddar or mexican cheese, shredded and divided
1/2 cup onion, chopped
1 medium tomato, chopped
1 cup shredded lettuce
1 can sliced olives (optional, I didn't use)

In a large bowl, combine the corn bread, egg and milk until blended. Spread into an 8 x 8 pan sprayed with cooking spray. Bake at 350 for 15 minutes. Combine taco meat and beans, spread over corn bread. Combine sour cream, 3/4 cup cheese and onion. Spread over meat mixture. Bake for 20 - 25 minutes longer or until heated through and cheese is melted. Sprinkle with tomato, lettuce and remaining 1/4 cup of cheese.