Simple, basic, how-to recipe. Meat thermometer required. Cook to internal temperature, not elapsed time. Time is approximate for a 5-pound roast. Any size roast will do, just cook to the correct internal temperature. Add 20 minutes for resting time.
Pat the rib roast dry with a paper towel or napkin.
Smear the cut ends of the roast with the butter. Place the roast (ribs down or fat side up) in roasting pan.
Sear the rib roast for 15 minutes at 450°F, then turn the oven to 325°F for the rest of the cooking time. Every 1/2 hour, baste the cut ends of the roast with the fat accumulated in the roasting pan.
Cook until rib roast reaches an internal temperature of 120°F Remove from oven, cover loosely with aluminum foil, and let sit approximately 20 minutes. The roast will continue to cook as it sits. Serve when the internal temperature reaches 130°F.