How to Make It
Preheat the oven to 400°. In a small bowl, beat the butter with the garlic, chopped thyme and chopped sage and season with salt and pepper.
Season the turkey inside and out with salt and pepper. Rub two-thirds of the herb butter inside the cavity and under the neck flap. Place the remaining butter in the cavity along with the thyme and sage sprigs. Tuck the wing tips under the bird and tie the legs together with kitchen string. Tuck the apple, rounded side out, under the neck flap. Fold the neck skin under the body and secure with a skewer.
Put the onion, carrot and celery in a large roasting pan. Set the turkey in the pan and add the neck and gizzard. Rub the turkey all over with olive oil. Roast the turkey in the lower third of the oven for 30 minutes. Reduce the oven temperature to 325° and continue to roast, basting occasionally, for 2 hours and 35 minutes longer, until an instant-read thermometer registers 165° when inserted in an inner thigh. Transfer the turkey to a carving board and let rest in a warm place for at least 25 minutes and up to 1 hour.
In a small bowl, cover the porcini with 1/4 cup of hot water. Let stand until softened, about 10 minutes. In a large skillet, melt the butter in the olive oil. Add the chanterelle mushrooms and the shallots and season with salt and pepper. Cook over moderate heat, stirring occasionally, until the mushrooms are golden brown and tender, about 8 minutes. Lift the porcini from the soaking liquid and add to the skillet. Cover and remove the skillet from the heat.
Set a coarse strainer over a medium bowl. Pour in the juices and vegetables from the roasting pan and press on the solids to extract as much liquid as possible. Skim the fat off of the juices and reserve 2 tablespoons. In a large saucepan, stir the reserved fat with the flour until smooth; cook over moderate heat until lightly browned, 2 to 3 minutes. Gradually whisk in the strained juices and the stock and bring to a simmer, whisking. Stir in the mushroom mixture and simmer over low heat, whisking often, until no floury taste remains, about 10 minutes. Season with salt and pepper.
Carve the turkey and serve with the gravy.