In the medium bowl, mix together the softened butter, parsley, sage, and shallots until the herbs and shallots are evenly distributed throughout.
Loosen the turkey skin and rub the butter mixture underneath. Sprinkle kosher salt and fresh ground black pepper on the skin.
In the large bowl, toss the vegetables with the olive oil, then sprinkle with more kosher salt and black pepper. Transfer the vegetables to the large roasting pan and spread to cover the bottom. Scatter the thyme and rosemary sprigs on top, then arrange the turkey pieces over the herbs and vegetables.
Roast in the preheated oven for 20 minutes, then reduce heat to 350° F/175° C. Continue roasting until the thermometer reads 150° F/66° C in each breast and 160° F/71° C in each leg, thigh, and wing. Some pieces will be done before others, and each piece should be removed as it reaches temperature. Place turkey pieces on a large platter and cover with foil. Leave the vegetables in the pan and continue cooking until they are fully tender, about 15 minutes more. Transfer the cooked vegetables to the platter with the turkey or a large bowl.
Strain the pan juices into the fat separator and let the fat rise to the top. Pour the juices (minus the fat) into the saucepan. Add the wine and bring to a boil, and cook until reduced by half, about 10 minutes. Mix the cornstarch and ½ cup water in a small bowl, then whisk it into the reduced liquid. Return to a boil and season with a little more salt and pepper to taste. Serve with the turkey and vegetables.