Heat oven to 400'F. Cook ground beef and 1/2 cup of the onion in 10" skillet until beef is brown; drain. Stir in barbecue sauce. Spoon into ungreased 13x9x2" baking dish; sprinkle with cheese.

Stir baking mix, milk and eggs until blended. Pour over beef mixture. Sprinkle with remaining onion.

Bake 25-27 minutes or until crust is light golden brown.