Preheat oven to 400F. Season turkey pieces all over with salt and pepper. Place on a large rimmed baking sheet and cover the pan with aluminium foil. It should be sealed.
Roast turkey for 30 minutes. Remove foil (keep it for later) and roast for an additional 15 minutes. Meanwhile, prepare the remaining ingredients.
Peel or scrub sweet potato and cut into 1 inch cubes. Cut onion into 8 sections. Cut celery into 1-inch sections. Combine all three vegetables in a bowl and toss with 2 tablespoons olive oil, 1/2 teaspoon salt and a few sprigs of fresh thyme.
Remove turkey from the oven and increase the temperature to 425F. Spread the vegetables around the pan in a single layer. Return to the oven and roast for 20 minutes.
Place the bread cubes in a bowl and pour over the chicken stock and 2 Tablespoons melted butter. Toss bread cubes with ground savory and more fresh thyme. Combine cranberries, chestnuts and green beans in the vegetable bowl. Drizzle with 1 Tablespoon olive oil and season with salt and pepper.
Remove pan from oven (yep, one more time!). Tuck the bread cubes around the turkey. Sprinkle the cranberries, chestnuts and green beans all over the sheet pan. Brush turkey with remaining melted butter. Roast everything for 10 minutes.
Remove pan from oven. Cover loosely with foil and rest for 10 minutes. Carve and serve.