Preheat oven to 400 degrees.
Heat an 8-inch cast iron pan or non-stick skillet with a cup of clarified butter. With a mandoline (Japanese or German) slice half the potatoes in very thin rounds, dry potatoes with a clean cloth. Starting from the center of the pan, overlapping slightly, place slices in a spiral going clock-wise. Repeat another spiral counter clock-wise. Sprinkle with salt and pepper. Drizzle with clarified butter and quickly, repeat process of layering, seasoning and drizzling, until the potato cake is about 2 inches high. Slice more potatoes as needed. Shake pan lightly to keep bottom from sticking. Place in oven to finish for 20 minutes. Use the remaining potatoes and butter in the same manner in another skillet. Test center of Pommes Anna for tenderness. Pour excess butter into a pot for future use. Remove from pan, drain on paper towel and cut into wedges.
