Arrange potato slices in layers in a gratin pan or baking pan, sprinkling salt and pepper over each layer. Pour sherry over the potatoes. Pour the melted butter over the potatoes. Make sure the potatoes are well coated.
Bake uncovered for 30-40 minutes or until potatoes are cooked, but not mushy, and they are slightly browned on top. Remove from oven, sprinkle with chopped fresh parsley.