
Combine chicken breasts with BBQ sauce, onion, brown sugar, salt, and barbecue seasoning in a 6-quart slow cooker.
Ensure the chicken is evenly coated with the sauce mixture.
Cover and cook on low for 6 or 7 hours, until the chicken is fully cooked and tender enough to shred.
Transfer the cooked chicken to a cutting board and use two forks to shred each breast.
Return the shredded chicken to the slow cooker and stir well to evenly coat it with the sauce.
Toast hamburger buns, assemble the sandwiches with coleslaw or pickles, and enjoy!