2) Working one at a time, slice each potato very thinly on the mandoline. It is important to work quickly here because the potatoes will discolour. Do not put the potatoes in water because this will wash off the starch.
3) Coat a 20cm nonstick saute pan with olive oil. Starting from the centre, make concentric circles of potato. Remember that eventually the bottom will be the top so it is important for the first circle of potato to look pretty.
4) Brush each layer with olive oil and every second or third layer sprinkle liberally with grated Parmesan and salt. After every layer of potato press the layer down so they compact. Repeat this process until all the potatoes are layered.
5) Place the pan of potatoes over a medium heat and cook until the olive oil begins to sizzle and the potatoes begin to brown on the bottom, about 10 minutes.
6) Transfer the pan to the oven and bake for 20 to 25 minutes.
7) Remove the pan from the oven and place a tight fitting lid on the pan. Drain the excess oil out of the side of the pan. THIS STEP IS EXTREMELY IMPORTANT!!! After the excess oil has been drained, completely flip the pan so the cake is turned out onto the bottom of the lid, then slide the cake off the lid back into the pan so the brown side of the cake is now up and the top becomes the bottom. We see now why draining the excess oil is important – if you attempt this without draining the oil it will drain out on your wrist and burn you.
8) Return the pan to the oven and bake for another 10 to 15 minutes or until the cake is fork tender. Cut into wedges and serve.