Peel the potatoes and slice thin. Butter a 10" round baking dish and melt remaining butter in a saucepan.
Layer the sliced potatoes in the baking dish. Drizzle each layer with a small amount of the butter, sprinkle with salt and pepper. Repeat layers until all the potatoes are used. Pour the remaining butter over the top.
Bake at 425F for 1 hour or until the top is crusty and the potatoes tender. Cut into wedges.