Clean the potatoes. Cut a thin slice of the potato to make a flat base and the potato stays stable while slicing (check out the video). Place the potato lengthwise between 2 wooden spatulas or chopsticks.
Cut the potato into very thin slices. Run the knife all the way down until it touches the chop sticks/spatula.
Place sliced potatoes on the baking tray. Brush potateos generously with olive oil. Rub with salt and pepper.
Place the potatoes on a tray. Bake for 30 minutes, then remove from oven. Bast the potatoes with the oil from the tray. Bake again for 20-30 minutes. By the end of baking the potatoes must have cooked thoroughly and slices would have fanned out fairly.
Meanwhile mix together melted salted butter, minced garlic, and minced rosemary.
Take out the potatoes, brush the rosemary garlic butter mix on potatoes, pushing through the garlic in between the slices.
Bake again for 15-20 minutes until the potatoe skin gets crispy and garlic turns golden brown. If you wish, brush the potatoes once again with the remaining oil from the pan.