Preheat the oven to 325 degrees.
Remove the neck and giblets from the inside of the turkey. They can be added to the bottom of the roasting pan or save them to use later to make turkey stock.
Separate about 4 springs of thyme and several sage leaves. Set aside.
Place the onion, thyme, sage, garlic, butter, salt and pepper in the roasting pan. You do not need to stir or mix it.
Place the turkey breast side up in the pan.
Take the 4 springs of thyme and several sage leaves and place between the skin and the breast meat.
Spray or rub olive oil on the turkey skin.
Loosely tent with aluminum foil over the top of the turkey.
Bake at 325°F. Insert a meat thermometer into the thickest part of the thigh and roast until the internal temperature reaches 165 degrees, or follow the recommended time for the size of your turkey. Baste the turkey every hour. During the final hour, remove the foil to allow the skin to turn golden. Check the turkey every 20 minutes, and once it reaches your desired level of golden brown, tent it with foil again and continue roasting until fully cooked.
Let rest for 45 minutes before carving. Once carved pour some of the broth from the pan over the meat to keep it moist until serving.