PLACE meat in slow cooker. Top with soup mix, onions and barbecue sauce; cover with lid.

COOK 4 to 6 hours on HIGH (or 8 to 10 hours on LOW). Remove meat from slow cooker; cut into small pieces or shred with fork. Return meat to slow cooker. Mix with sauce.

SPOON meat mixture evenly onto bottom halves of buns; top with Singles. Cover with tops of buns.