Preheat the oven to 350°F. Position an oven rack one level below the center of the oven.

Remove the neck and giblets from the turkey. Place the turkey breast-side up on a roasting rack inside a roasting pan.

Cut the onions and orange into large pieces. Place some of the onion, all of the orange, and half of the rosemary and thyme inside the turkey cavity.

Tuck the wings underneath the turkey. Tie the legs together with kitchen twine, if desired.

Pat the turkey dry with paper towels. Rub the softened butter evenly over the skin, then season with salt and pepper.

Arrange the remaining onions, rosemary, and thyme around the turkey in the roasting pan.

Loosely tent the turkey with aluminum foil to prevent the skin from browning too quickly.

Roast for approximately 14–15 minutes per pound, checking for doneness with a meat thermometer. The turkey is done when the internal temperature reaches 165°F in the thickest parts of the breast and thigh.

Remove the turkey from the oven and let it rest for 30–60 minutes before carving.

Transfer to a serving platter, carve, and serve.