01 - Coat the inside of the slow cooker vessel thoroughly with non-stick cooking spray.
02 - Whisk together cayenne pepper, smoked paprika, and garlic salt in a small mixing bowl until evenly combined.
03 - Sprinkle the prepared spice blend evenly over the chicken breasts.
04 - Place the seasoned chicken breasts firmly along the bottom of the slow cooker insert.
05 - Scatter light brown sugar over the chicken. Drizzle the honey and white vinegar evenly over the surface.
06 - Distribute the unsalted butter pieces across the chicken, then secure the lid on the slow cooker.
07 - Set the slow cooker to low and cook for 4 hours, or use high setting for 2 hours, until chicken is fully cooked and tender.
08 - Transfer the cooked chicken to a heat-safe plate and shred using meat claws or forks. Return shredded chicken to the slow cooker and stir to coat in the cooking juices.
09 - Spoon hot shredded chicken onto hamburger buns. Top with sliced pickles if desired and serve immediately.