Meanwhile, melt 2 tablespoons of the butter in a large nonstick skillet. Add half of the apples in a single layer and cook over high heat, turning once, until golden and crisp-tender, about 5 minutes. Add half each of the brown sugar and cinnamon and cook, stirring gently, until the apples are lightly caramelized, about 2 minutes. Transfer the apples to a plate. Wipe out the skillet and repeat with the remaining butter, apples, brown sugar and cinnamon.