01 - Combine chicken thighs, diced onion, sliced carrots, celery, minced garlic, chicken broth, dried thyme, parsley, rosemary, bay leaf, black pepper, and salt in the slow cooker. Stir thoroughly to distribute ingredients evenly.
02 - Cover the slow cooker and cook on low setting for 4 hours until chicken thighs are very tender and easily shredded.
03 - Remove cooked chicken from the slow cooker, shred using two forks, and return shredded meat to the stew. Remove and discard the bay leaf.
04 - Stir frozen peas and heavy cream into the slow cooker, mixing gently to incorporate.
05 - In a medium bowl, whisk together all-purpose flour, baking powder, and salt. Cut in cold butter cubes using fingers or a pastry cutter until mixture resembles coarse breadcrumbs. Add whole milk and fresh parsley, stirring gently just until combined. Do not overmix.
06 - Drop tablespoon-sized portions of dumpling dough onto the surface of the simmering stew, keeping dumplings above the broth surface rather than submerged.
07 - Cover and cook on high setting for 1 hour until dumplings are puffed and cooked through.
08 - Ladle into bowls and serve hot. Garnish with additional fresh parsley if desired.