Preheat your oven to 400F degrees. Move oven rack to center.
Pat chicken thighs dry with paper towel and season all over with salt and black pepper.
Heat olive oil in a cast iron skillet (10-inch) over medium heat. Place the chicken thighs skin-side down and sear until the skin is golden and crispy. It’s about 5 minutes (they will not be cooked through at this point).
Flip your chicken over once the skin is crispy. If your chicken thighs releases a lot of fat, dispose it using a spoon.
Place butter in the same skillet. When the butter is melted, add minced garlic. Stir the garlic around the pan for 30 seconds.
Place the whole skillet in the oven and bake for 30 mins for until chicken gets the internal temperature at 165°F.
When the chicken is cooked, spoon some of the garlic butter sauce over the top of each chicken thigh. Top with parsley before serving.