If you are cooking any parts of a chicken from frozen, there is an increased risk for foodborne illness. To kill any pathogens in the chicken, be sure to cook the meat to an internal temperature of at least 165°F (74°C). Always prepare from frozen chicken in the oven or on the stovetop and, as a rule of thumb, cook it about 50 percent longer than you would thawed meat.
For example, it would take about two hours to roast a thawed 5-pound (2.25 kg) roasting hen at 350°F (177°C). If frozen, a similarly sized chicken would take about three hours to cook thoroughly at the same temperature. Check the internal temperature of the meat by inserting a meat thermometer into thickest part of the breast and the innermost part of the thigh and wing. If the thermometer does not ready 165°F (74°C), continue cooking the bird. Do not try to cook the frozen chicken in a slow cooker. The appliance will not get hot enough to kill the pathogens in the meat. It also leaves the meat sitting for too long at unsafe temperatures.