
Preheat the oven to 450°F. Soften butter, then stir in rosemary, garlic, salt, pepper, and thyme to create a garlic butter paste.
Rub the paste all over the prime rib roast and wrap aluminum foil around all exposed rib bones. Place the roast in the center of a roasting pan with a rack.Roast at 450°F for 15 minutes. Then, reduce the temperature to 325°F and cook for approximately 2 hours. (Check your meat thermometer for desired doneness).
Remove from the oven and tent with aluminum foil. Let rest tented for 15 minutes. Slice rib roast, serve, and enjoy!