In a large skillet, cook the beef and onion over medium heat until meat is no longer pink; drain and set aside. In a small bowl, combine the corn bread mix, salt, baking soda, corn, milk, oil and eggs.
Pour half of corn bread mixture in a greased 13 in. x 9 in. x 2in. baking dish. Layer with half of the cheese and all of the beef mixture. Top with remaining cheese. Carefully spread remaining batter over top.
Bake, uncovered, at 350 degrees F for 40 - 45 minutes or until a toothpick inserted near center comes out clean.