Heat a Dutch oven coated with cooking spray over medium-high heat. Add onion and garlic; saut? 5 minutes. Stir in sherry and the next 4 ingredients (sherry through soup), and bring to boil. Add chicken pieces; bring to a boil. Cover, reduce heat, and simmer 35 minutes or until chicken is tender. Remove chicken pieces from cooking liquid. Place chicken in a bowl, and chill 15 minutes. Remove chicken from bones, and cut meat into bite-size pieces. Discard the bones. Add chicken to pan; stir in peas. Combine water and cornstarch in a small bowl; stir with a whisk. Add cornstarch mixture to pan; stir well. To prepare dumplings, combine baking mix and milk. Drop the dough into chicken mixture to form 16 dumplings. Bring to a simmer; cook 20 minutes, stirring occasionally. Cover and cook for 10 minutes or until the dumplings are done. Garnish with parsley, if desired.