Remove the roast from the refrigerator 4 hours before you start to cook it. The roast must be brought to room temperature to insure even cooking. Larger roasts can sit out for 6 hours.

Cut the bones from the roast then season entire roast with kosher salt and pepper. Place roast back over the bones and tie them together using kitchen twine. Removing the bones now makes carving much easier.

If you want to roast it boneless, then do not attach the bones back or use a boneless rib roast.

Let roast sit until brought to room temperature. You can also place the roast on rack over a baking sheet and keep in the refrigerator overnight to create a crispier crust on your prime rib. You will still need to bring the roast to room temperature before cooking it.

Preheat your oven to 500°F. Place prime rib on a roasting pan with rack, fat side up.  Insert a meat thermometer into the thickest part of the roast, making sure that it does not touch bone.

Cook your roast using this formula: Multiply the exact weight times 5 minutes, then round up to the nearest minute. For example, a 9.7lb roast will cook 9.7x5=48.5 or 49 minutes.

Once cooked for this exact time, turn oven off and let it sit in the oven for 2 hours. Do not open the oven door during this time. This will yield a perfect medium rare center for your roast. If your thermometer reads 125ºF before the 2 hours is done, remove the roast.

While the roast is cooking, prepare the horseradish butter. In a bowl, thoroughly combine the butter, horseradish, garlic, chives, salt and pepper.

Spoon butter onto a sheet of plastic wrap. Gently form into a small log as you wrap up the butter. Refrigerate until firm. Add a pat of butter with each serving of prime rib.