Mix meat, stuffing mix, 1-1/4 C water, and the onions until well blended. Shape into six 1/2" thick patties. Place in 15x10x1" baking pan.
Bake 25 minutes or until cooked through.
Meanwhile, in a large skillet sprayed with non-stick spray, saute mushrooms 5 minutes or until lightly browned. Add barbecue sauce and remaining 1/4 C water. Cook until heated through. Serve over patties.