Prime Rib - Made this for New Years Eve dinner party. Absolutely perfect results. I used an digital internal [external part sits on countertop] OXO thermometer. 500 degrees 25 minutes, 300 degrees for about 45 minutes and then bumped the temp up to 325 to finish. Definitely takes longer than 20-30 minutes at 300 for a 4 rib roast. Plan and use a thermometer!