HEAT oven to 375°F.
PLACE meat on foil-covered rimmed baking sheet or in shallow foil-lined roasting pan. Reserve 2 Tbsp. barbecue sauce for later use; brush meat with 3 Tbsp. of the remaining sauce.
BAKE 15 min. Turn meat over; brush with remaining barbecue sauce. Bake 15 min. or until done (160°F). Remove from heat. Brush with reserved barbecue sauce; let stand 5 min.
MEANWHILE, melt butter in medium saucepan on medium heat. Add onions; cook 3 min., stirring occasionally. Add water and apples; bring to boil. Stir in stuffing mix; cover. Remove from heat; let stand 5 min.
FLUFF stuffing with fork. Serve meat with stuffing.