Preparation: Preheat your oven to 325°F (165°C). Remove the turkey giblets and pat the turkey dry with paper towels.
Season the Turkey: Rub the softened butter all over the turkey, including under the skin. Sprinkle salt, pepper, garlic powder, onion powder, thyme, and rosemary evenly over the turkey.
Stuff the Turkey: If using stuffing, mix the bread cubes, onions, celery, sage, salt, and pepper in a bowl. Moisten with chicken broth until combined but not soggy. Stuff the cavity of the turkey loosely.
Prepare the Roasting Pan: Place the quartered onion, carrots, and celery in a roasting pan. Add the turkey on top, breast-side up. Pour chicken broth into the pan to keep the turkey moist during cooking.
Roast the Turkey: Cover the turkey loosely with aluminum foil and roast in the preheated oven. Remove the foil during the last hour to allow the skin to brown. Cook until the internal temperature reaches 165°F (75°C) in the thickest part of the thigh.
Rest: Once cooked, remove the turkey from the oven and let it rest for at least 30 minutes before carving. This allows the juices to redistribute and keeps the meat moist.
Carve and Serve: Carve the turkey and serve with your favorite sides. Enjoy your delicious roast turkey!