Rub the prime rib roast with olive oil, garlic, rosemary, salt, and pepper.
Place the roast on a rack in a roasting pan, fat side up.
Roast in the preheated oven for 15 minutes to sear the outside.
Reduce oven temperature to 325°F (163°C) and continue roasting for about 75 minutes or until internal temperature reaches 130°F (54°C) for medium rare.
Remove from oven and let rest for at least 15 minutes before slicing.
Notes
For best results, use a meat thermometer and let the roast rest to retain juices before carving.