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.
Meanwhile, for dumplings, whisk together flour, baking powder, salt, poultry seasoning, and pepper in medium bowl.
Whisk buttermilk, egg and melted butter in small bowl. Add buttermilk mixture to flour mixture with fork, stirring just until moistened. Gently drop dough by ¼ cupfuls into simmering soup with scoop or measuring cup, leaving space between dumplings. Cover and simmer about 20 minutes or until wooden pick inserted in center of dumplings comes out clean. Garnish with parsley.
Prep Tip: You can use 1 (16.3-ounce) can of refrigerated homestyle biscuits as a substitute for homemade dumplings! Drop into soup as directed for dumplings and proceed with recipe as directed.
Prep Tip: 1 cup milk may be used in place of buttermilk.
Prep Tip: 3 cups of frozen peas and carrots can be used in place of fresh carrots and frozen peas. Add as directed for peas.
Pro Tip: Cooked, leftover turkey is good for 3 to 4 days. To save for even longer, pop it in the freezer to save for up to 6 months!
Pro Tip: If you don't have baking powder, but baking soda - no worries! Baking powder is just baking soda plus an acid (think cream of tartar, lemon juice or white vinegar). To substitute your baking powder with baking soda plus an acid, mix ½ teaspoon of acid with ¼ teaspoon of baking soda. This ratio will give you an equivalent of 1 teaspoon of baking powder.