Place onion in the bottom of slow cooker then top with chicken. Place seasonings on top of chicken.
Pour over condensed soup and broth. Cover and cook on high until the chicken is cooked through, approximately 3 hours.
Shred chicken. Stir in celery, carrots, and peas. Cut biscuits into small pieces and then stir (or if you prefer to place on top) into chicken mixture. Spoon liquid over any biscuits at the top. Cook on high until biscuits are cooked through, approximately 1 hour more.