- Whisk water, poultry seasoning, salt, and black pepper together in a bowl; add chicken to bowl and turn to coat.
- Pour 1/2 of the chicken broth into a slow cooker; add chicken and poultry seasoning mixture. Layer onion, carrots, and celery, respectively, over chicken. Dot butter over vegetables; pour celery soup and chicken soup over vegetables and sprinkle rosemary on top.
- Cook on High for 3 1/2 to 4 1/2 hours. Remove chicken from slow cooker and shred with two forks; return chicken to slow cooker. Add biscuit dough pieces to chicken mixture. Cook on High for 1 1/2 hours.