01 - Place the boneless, skinless chicken breasts in an even layer across the bottom of the slow cooker.
02 - In a mixing bowl, whisk together the packed brown sugar, low-sodium soy sauce, minced garlic, apple cider vinegar, smoked paprika, and black pepper until smooth and fully combined.
03 - Pour the sauce evenly over the chicken breasts, ensuring each piece is well coated.
04 - Cover the slow cooker and cook on low for 4 hours or on high for 2 hours, until the chicken reaches an internal temperature of 165°F and is fork-tender.
05 - Remove the chicken from the slow cooker and shred using two forks or slice into portions. Spoon the accumulated cooking juices and sauce generously over the top.
06 - Finish with a sprinkle of chopped fresh parsley and sliced green onions. Serve immediately while hot.