In a skillet, brown the onion and ground beef together until beef is cooked through.
Drain the grease and rinse meat under hot water. Return to the skillet.
Stir in kidney beans and barbecue sauce.
Pour into greased 2 quart casserole dish.
In a bowl, stir together the Bisquick, milk and egg until well combined.
Pour batter over meat.
Bake 400 degrees, uncovered for 30 minutes.