Preheat the oven to 475°F.

Pat turkey dry inside and out with paper towels; brush skin with butter.

In a small bowl, combine sage, garlic, salt and pepper.

Loosen skin over the turkey breast meat with your fingers and work a little of the sage mixture under the skin and over the meat.

Sprinkle remaining mixture over skin and in the cavity of the turkey.

Tie the legs together with kitchen twine and tuck the wings under the body; place in a large roasting pan fitted with a rack and roast 20 minutes.

Lower oven temperature to 350°F, tent breast loosely with a piece of foil and roast 1 hour longer.

Remove turkey from oven, remove foil and baste with pan juices.

Arrange apples and onions around turkey and continue to roast (without foil covering) until a meat thermometer inserted into the thickest part of the thigh registers 165°F or juices run clear (not pink) when you poke thigh with a paring knife, about 2 hours more.

Transfer turkey to a platter and let rest 30 minutes before carving.

Cover pan with foil to keep apples and onions warm and serve alongside turkey.