Place the chicken breasts in the slow cooker. Add the chicken broth, cream of chicken soup, carrots, celery, onion, garlic powder, thyme, salt, and pepper. Stir to combine.
Cover and cook on low for 6 hours.
Remove the chicken, shred it with two forks, and return it to the slow cooker. Stir in the heavy cream.
Add the quartered biscuit pieces and frozen peas. Stir gently to submerge the biscuits.
Cover and cook on high for 1 more hour until the dumplings are cooked through and the sauce has thickened.