Thinly slice your potatoes as thin as a crisp using a mandolin or food processor. Put the slices in a bowl.
Warm the cream in a saucepan over a medium-high heat and bring to a simmer. Lower the heat and leave simmering until slightly thickened (about 5-10 minutes). Add the salt, pepper and garlic and pour this over the slices of potato and mix in the salt.
Meanwhile, heat the oven to 140°C.
Line a 900g loaf tin with baking parchment and layer the spud slices one by one, overlapping them neatly to build a loaf. Place a sheet of baking parchment on top and bake the loaf for 3 hours, until cooked through.
Add some weight on top of the cooked, covered loaf. Tins of baked beans are good for this. Transfer it all to the fridge for 12 hours to set. The waiting is the hardest part.) Then, remove the tins and parchment and turn out the loaf. Trim off each end so that the loaf is perfectly straight, and cut the loaf into 2.5cm slices (you'll get about 6 or 7 slices altogether).
Pour the oil into a deep-fat fryer or a heavy-based saucepan (don't let it come more than halfway up the inside of the pan). Place the pan over a high heat and get the oil to 190°C. Fry the potato portions in batches for about 1-3 minutes (if you're cutting to these portions), or until golden. Drain each batch on kitchen paper while you fry the remainder. (You can cut into slabs or squares, just adjust the frying time as necessary.) Once they're all fried, sprinkle with more salt.