In large bowl, combine the corn bread mix, egg, and milk until mixed well.
Spread in 13×9 baking dish sprayed with cooking spray.
Bake at 350 for 15 minutes
Meanwhile, cook the ground beef & drain.
Add taco seasoning as directed on packet.
Combine taco meat, onions, and beans and spread over top of cornbread.
Top with shredded cheese.
Bake for 20 minutes.
Garnish with sour cream and green onions, if desired.