Preheat oven to 400°F.
In a bowl, combine potatoes with salt, pepper, nutmeg and Dijon. Brush a 10-inch glass or ceramic pie plate, or an oven-safe, nonstick skillet or tart pan liberally with about 2 tablespoons butter. Line the pan evenly with potatoes to form a crust to the edge of the pan—tuck in any straggling bits of potatoes as they will burn. Brush the top of potato crust with remaining melted butter and bake about 30 minutes to golden; let cool.