Preheat oven to 400 degrees. Spray an 8x8 inch baking dish with non-stick spray. Set aside.
In a large skillet brown ground beef, breaking apart over medium high heat, until cooked through. Drain away any fat.
Pour in the can of Manwich, stir to combine.
Spread the meat mixture into the bottom of the prepared pan.
While the ground beef is cooking prepare the cornbread mix. In a bowl combine cornbread mix, egg, and milk. Stir to combine (a few lumps are OK.)
Pour over meat mixture.
Place in oven and bake for 15 minutes, or until golden brown and the cornbread is set.