Preheat the oven to 400°F (204°C).
Pat the chicken thighs dry and season both sides with salt and pepper.
Heat 2 tablespoons olive oil in a 12-inch cast iron skillet over medium-high heat until shimmering.
Add the chicken thighs skin-side down and cook 5–6 minutes until the skin is golden and crispy, then flip and cook 2–3 minutes more; remove chicken to a plate.
Reduce heat to medium and add 2 tablespoons butter to the skillet; when melted, add the halved potatoes and cook 5–6 minutes until lightly browned.
Stir in the minced garlic, chopped rosemary, chopped thyme, and lemon slices, and season the potatoes with salt and pepper.
Return the chicken thighs to the skillet, nestling them on top of the potatoes and lemon slices.
Transfer the skillet to the preheated oven and bake uncovered 25–30 minutes, until the chicken is cooked through and potatoes are tender.
Remove from oven, let rest a few minutes, then serve hot with optional extra herbs or lemon wedges.
