Tex-Mex Cornbread Casserole

I absolutely love this.  You can put anything in the filing, this is another chili with corn type recipe but with a sweet corn bread on top.   Also to make this an even easier recipe you could use leftover chili or canned chili with the cornbread on top but I like this recipe a lot especially with the little bits of chilies in it.

1 lb of Ground Beef
1 15 oz. Can Diced Tomatoes
1 small onion
1 Package Taco Seasoning or chili powder
1 can black beans or other
1 Can Kernel Corn – any size (Drained)
1 Can Sliced Black Olives (Drained) (Optional for those that don't like them)
1 can diced green chiles (optional)
1 sm. can tomato sauce
3 Cups Shredded Cheese
2 Jiffy Corn Muffin Mix

Note:This makes a lot. I usually make the whole batch and put in 2 smaller baking dishes, 1 to eat and 1 to freeze, then I mix only 1 box of the corn bread with 1 c. cheese and place over the one we bake. 
Pre-heat oven according to Jiffy Muffin instructions. Grease a 13x9 dish and set aside. Brown ground beef and diced onion. Once onion is clear and beef cooked, stir in diced tomatoes (with juice) and taco seasoning. Stir in corn, beans, black olives, tomato sauce and chiles. Simmer for about 5-10 minutes until some of the liquid evaporates. Dump mixture in bottom of casserole. Sprinkle 1 cup of cheese on top. Next mix cornbread muffin mix according to package directions and add 2 cups of cheese to the mix. Pour on top of meat mixture and spread evenly. Bake about 20-25 minutes until the cornbread is done.