Preheat oven to 475 degrees Fahrenheit. Season chicken thighs with thyme, salt and pepper. Heat oil in cast iron skillet over high heat. Reduce to medium heat, and cook chicken about ten minutes on each side.
Transfer skillet to oven and cook for another twenty minutes or until chicken reaches an internal temperature of 165 degrees Fahrenheit. Flip chicken half way through cook time for even cooking on both sides. Serve immediately.