To freeze: Mix chicken, carrot, celery and parsley in 1-quart resealable freezer plastic bag. In small bowl, mix flour, baking powder, salt and pepper. In 1-quart saucepan, heat milk and butter over medium heat until warm and butter is melted. Add warm milk mixture to flour mixture; stir until just combined. Transfer to surface sprinkled with flour; knead lightly once or twice until smooth. Using rolling pin sprinkled with flour, roll to 1/8-inch thickness. Using knife, cut rolled-out dumpling dough into 1 1/2x1-inch strips. Transfer to 1-quart resealable freezer plastic bag. Freeze both bags up to 3 months. When ready to serve: In 4-quart saucepan, heat broth to boiling over high heat. Reduce heat to medium; stir in contents of both bags. Heat to simmering; cook uncovered 7 to 8 minutes, stirring occasionally, until dumplings are cooked through and tender.