Pat the chicken dry and season with salt and pepper.
Heat the olive oil in a large heavy skillet (preferably oven safe) over medium high heat. Place the chicken thighs skin side down in the skillet and let sear without moving them until the skin is fairly crispy and golden brown, about 8 minutes; adjust the heat as needed. Turn the thighs over, skin side up, and continue to cook, without moving the thighs, until the bottoms are golden brown, about 5 more minutes.
Meanwhile, in a small saucepan melt the butter with the garlic over medium-low heat. Season with salt and pepper. You can also do this in a microwave in a small microwave-safe bowl.
Drizzle the garlic butter over the chicken and place in the oven if your skillet is oven safe. If your skillet is not oven-safe, just transfer the chicken to a baking dish and drizzle over the garlic butter, then bake it in that.
Bake for 30 to 40 minutes until the chicken is cooked throughout and the chicken is deep golden brown with crispy skin. If you are baking the chicken in the already hot skillet, it will probably take 30 minutes, but if you have transferred it to a cool baking dish, it may take about 40 minutes.