Preheat oven to 425°F. Season chicken with salt and pepper. Heat oil in an ovenproof skillet over medium-high heat. Place chicken skin side down in skillet and cook until golden brown, about 5 minutes. Turn chicken over and brown other side. Add thyme and garlic to pan and place in oven. Roast until an instant-read thermometer inserted in thickest part of breast registers 165°, 15–20 minutes.