Easy Leftover Turkey Dumpling Soup

For soup, heat 2 tablespoons butter over medium heat in large Dutch oven. Add onion, carrots and celery; cook, stirring frequently, 5 to 6 minutes or until tender. Stir in remaining 4 tablespoons butter until melted. Stir in flour until combined; cook, stirring constantly, 2 minutes. Gradually stir in broth, salt and pepper. Bring to a boil; reduce heat to medium-low, cover, and simmer 30 minutes. Stir in turkey and peas; return mixture just to a boil.