Slice the potatoes very thinly using a mandolin. Place the potato slices in a large bowl of water to keep from browning.

Heat about 3" of oil in a large pot, fryer or wok (we love using our wok) to 350F. Pat potatoes dry in batches (8 to10 at a time) and fry until golden brown. Drain well with a slotted spoon. Do not pat dry the potatoes as the toppings won't adhere. Place potatoes in a bowl with a pinch of rosemary, cheese and salt to taste and gently toss. Place on a cookie sheet to dry. Repeat until all potato slices are cooked.