In the restaurant field, the Prime Rib Roast that is prepared usually weighs about twenty-five pounds and has seven bones. This is too large and too costly for the average size family who really only needs about a seven pound roast with two bones.
If you wish well brown end cuts, start your roast, which has its ends brushed with fat, in a 450 degree oven for twenty-five minutes, and then lower the oven to 340 for the balance of the baking time. To reduce shrinkage, just start and bake the roast in the 340 degree oven. It takes about 15 minutes per pound to reach the desired doneness, depending how you like it cooked. A meat thermometer is a good way to prevent over-baking, but remember not to test next to the bone which will stay rarer longer. I remove my roast from the oven at 130 degrees, because it will continue to cook during the thirty minutes that you should allow it to rest. Resting allows the juices to properly redistribute. A roast is also done when a metal skewer that has been inserted in it, feels BARELY WARM against the space between your lip and your chin.
It is best to use a shallow pan. I like to put the meat in the pan, rib side down, on a rough cut mirepoix, which is celery, carrots, and onions. I also season the roast with salt and pepper and springs of fresh rosemary.
While the roast is resting on a platter, remove the mirepoix and deglaze the pan with a cup or so of beef stock. You can enrich this au jus by swirling a couple of table spoons of butter into the juice.