01 - Place chicken, diced onion, sliced carrots, sliced celery, minced garlic, dried thyme, dried parsley, bay leaf, salt, and black pepper into the slow cooker. Pour in the chicken broth and stir to combine all ingredients.
02 - Secure the lid and cook on the low setting for 5 hours, or until the chicken is exceptionally tender.
03 - Carefully remove the cooked chicken from the slow cooker. Shred the chicken using two forks and return it to the pot. Discard the bay leaf. Stir in the heavy cream until fully incorporated.
04 - In a separate medium bowl, combine the all-purpose flour, baking powder, and salt. Incorporate the cold, cubed butter using your fingertips or a pastry blender until the mixture resembles coarse crumbs. Gently stir in the whole milk and optional fresh parsley until just combined; avoid overmixing.
05 - Increase the slow cooker setting to high. Drop spoonfuls of the prepared dumpling dough, approximately 2 tablespoons each, onto the surface of the simmering soup.
06 - Cover the slow cooker and cook on high for 1 hour, or until the dumplings are puffed and thoroughly cooked through.
07 - Taste the dish and adjust seasonings as necessary. Serve hot.