Combine Stew Ingredients: Place the chicken at the bottom of a 6-quart slow cooker. Top with the chopped onion, carrots, celery, and minced garlic. In a separate bowl, whisk together the chicken broth, cream of chicken soup, thyme, rosemary, pepper, and salt. Pour this mixture over the chicken and vegetables. Add the bay leaf and stir gently to combine.
Slow Cook: Cover the slow cooker and cook on LOW for 6-8 hours or on HIGH for 3-4 hours, until the chicken is cooked through and tender.
Shred the Chicken: Once cooked, carefully remove the chicken from the slow cooker and place it on a cutting board. Discard the bay leaf. Use two forks to shred the chicken into bite-sized pieces. Return the shredded chicken to the slow cooker and stir.
Prepare Dumpling Dough: About 45 minutes before serving, prepare the dumplings. In a medium bowl, combine the baking mix, milk, and fresh parsley. Stir with a fork just until a soft dough forms. Do not overmix.
Cook the Dumplings: Turn the slow cooker to HIGH. Drop rounded tablespoons of the dumpling dough onto the surface of the hot stew, leaving a little space between each one. Cover the slow cooker and cook for 30-45 minutes, or until a toothpick inserted into the center of a dumpling comes out clean. Do not lift the lid during this time to ensure they steam properly.
Thicken and Serve: If you prefer a thicker stew, stir in the cornstarch slurry during the last 15 minutes of cooking. Serve the chicken and dumplings hot, garnished with extra fresh parsley if desired.