Preheat oven to 450 degrees F. Pat the room-temperature standing rib roast (prime rib roast) dry with paper towels or napkins. Smear the cut ends only of the roast with the butter.
Previously Frozen Roast: If your prime rib roast is frozen, let it thaw completely in the refrigerator. Remove the roast from the refrigerator about 2 to 4 hours before cooking to let it come to room temperature. Depending on the size of your roast, the time to come to room temperature may vary. I can not give you an exact time on this. Use your best judgment!
Room Temperature: To cook evenly, the roast must not be cold - let it stand at room temperature, loosely covered, for about 2 to 4 hours. This time can vary depending on how big or small your roast is. I can not give you an exact time on this. If you do not let the roast come to room temperature, if will take longer to cook your roast, your roast won't cook evenly, and you will end up with well-done slices on the end and raw meat in the center. Use your best judgment on room temperature times!
Do NOT salt the outside of your prime rib roast, as salt draws out moisture from the meat while cooking. You can use a prime rib rub containing other seasonings if desired, but I find it is not necessary. I know that some people do salt their prime rib roast before cooking, but trust me and do no salt - the result will be a juicy, delicious roast to serve your family and guests!
Roasting Pan: Place the roast, ribs down or fat side up, in a heavy stainless-steel Roasting Pan or other metal roasting pan. Select a roasting pan that has sides at least 3-inches deep. (I do not recommend using nonstick pans, as these pans yield fewer of the cooked-on bits that make the tasty au jus juice or gravy.) The rib bones are a natural rack; you will not need a metal one.
Cooking Temperatures: Sear the rib roast for 15 minutes at the higher oven temperature (450 degrees F.), then turn the oven to the lower temperature (325 degrees 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. Do Not Cover the roast.
You will want to estimate about 12 minutes per pound of meat for the cooking time. See charts to make it easy to determine Prime Rib Roast Cooking Times. About 45 minutes before the estimated end of the roasting (bake) time, begin checking the internal temperature (use a good instant-read digital meat thermometer). Play it safe and start checking early, as you do not want anything to go wrong. This is even more important if you are adjusting for High Altitude Baking.
If you ignore every other bit of advice I have given, please pay attention to this: For a perfectly cooked rib roast, invest in a good meat thermometer. Internal temperature, not time, is the best test for doneness and you do not want to blow this meal!
This is the type of cooking and meat thermometer that I prefer and use in my cooking. I get many readers asking what cooking/meat thermometer that I prefer and use in my cooking and baking. I, personally, use the Thermapen Thermometer shown in the photo on the right. To learn more about this excellent thermometer and to also purchase one (if you desire), just click on the underlined: Thermapen Thermometer.
When checking the temperature of your prime rib roast, insert meat thermometer so tip is in thickest part of beef, not resting in fat or touching bone. Cook until rib roast reaches an internal temperature of 120 degrees F. (or your desired temperature). See chart to determine Prime Rib Roast Internal Cooking Temperatures for rare, medium-rare, medium, medium-well and well-done. Remove from oven, cover loosely with aluminum foil, and let sit approximately 15 to 20 minutes. Cutting into the meat too early will cause a significant loss of juice. Do not skip the resting stage.
Residual Heat or Carry-Over Cooking: Remember, the rib roast will continue to cook as it sets. The internal temperature will rise to 125 degrees F. to 130 degrees F. (medium rare) in approximately 15 to 20 minutes. If allowed to rest as long as an hour, the internal temperature will rise even higher. So, pay attention to how long you let the cooked prime rib roast sit.
Holding Cooked Rib Roast: To hold cooked roast until serving time, immediately turn off the oven and leave the door ajar after removing roast. Let roast sit 15 minutes on the counter and then return roast to the oven, door closed, for up to an hour or even 2 hours for the biggest roasts. Check the temperature every 15 minutes. If will rise approximately 10 degrees F. at first, then gradually subside.
If Using a Convection Oven: Using a convection oven can cut as much as 25% off the cooking times listed for the regular oven. It is also easier for your roast to dry out and cook too much in the convection oven. Watch the roast carefully and please use a cooking thermometer to know when the roast is done and should be taken out of the oven.
Perfect Prime Rib Roast Recipe https://whatscookingamerica.net/beef/classicprimerib.htm