Place the seasoned Chateaubriand on a sheet pan. Roast the Chateaubriand in the preheated oven for about 10-15 minutes per pound, or until the internal temperature reaches your desired level of doneness. Use a meat thermometer to check the temperature. For medium-rare, aim for an internal temperature of around 130 degrees. Most ovens vary in true heat, so to be safe, check at 35 minutes