Spray two baking sheets lightly with some of the oil. Using a mandoline or hand-held slicing machine slice the potatoes crosswise 1/8-inch thick and arrange them in one layer on the baking sheets. Spray slices lightly with the oil and bake in a preheated 375 degree oven for 25-30 minutes or until they are golden throughout. (They will brown at different rates.) Transfer them to paper towels and sprinkle them with salt and rosemary, if desired, while they are still hot.
Courtesy of Gourmet Magazine