Place the chicken breasts in a slow cooker and pour the barbecue sauce over them. Cook on low for 6-7 hours or high for 3-4 hours until the chicken is cooked through and tender.

Once cooked, remove the chicken from the slow cooker and shred it using two forks. Return the shredded chicken to the slow cooker and mix it with the remaining barbecue sauce.

Toast the hamburger buns on a grill or stovetop skillet until golden brown. Spoon the BBQ chicken mixture onto the bottom half of each bun. Top with coleslaw and pickles if desired, then place the top half of the bun on each sandwich.

Serve the BBQ chicken sandwiches warm on a platter with additional barbecue sauce on the side.