1 Preheat oven to 375 degrees F (190 degrees C). 2  Place thighs in a baking dish. Season chicken thighs on all sides with garlic powder and onion flakes.  Bake chicken in the preheated oven until no longer pink at the bone and the juices run clear, about 30 minutes. An instant-read thermometer inserted into the thickest part of the thigh, near the bone should read 165 degrees F (74 degrees C).