To prepare a leftover turkey soup with rosemary parmesan dumplings recipe, you'll first need to prepare your turkey. Cut the turkey into 14-inch thick slices. Place the slices in the bottom of crock-pot and cook on medium-high heat until the meat is no longer pink and the juices run clear. Remove the pieces from the pot and set aside. In the same pot, heat the olive oil over medium heat. Add the chopped rosemary, parsley, and thyme. Cook, stirring frequently, until fragrant, about 5 minutes. Stir in 1/2 cup of the reserved turkey stock. Bring the mixture to boil, then reduce the heat to medium. Simmer, covered, for 30 minutes, or until thickened. Serve with sour cream, if desired.