Thaw the turkey if frozen, ideally in the refrigerator for at least 24 hours per 4-5 pounds.
Preheat the oven to 325°F (165°C).
Prepare the herb butter by mixing softened butter with chopped herbs, salt, and pepper.
Loosen the skin on the turkey breast and thighs carefully without tearing it.
Rub the herb butter under the skin and all over the outside of the turkey.
Stuff the cavity of the turkey with quartered onion.
Place the turkey in a roasting pan and tent it loosely with foil.
Roast the turkey according to its weight, approximately 13-15 minutes per pound.
Remove the turkey from the oven and let it rest for at least 30 minutes before carving.
While the turkey rests, prepare the gravy with drippings.
Serve the turkey with homemade gravy and enjoy.