Preheat oven to 350ºF.

Using a mandoline, carefully slice potatoes about 1/8-inch thick. If you do not have a mandoline use a freshly sharpened knife and slice as thinly and evenly as possible.

Place potato slices in a large mixing bowl and toss with oil, rosemary, and salt. Be sure to evenly coat potato slices, use a dash more oil as needed to ensure even coverage.

If using a gas oven it is best to bake in the bottom half of the oven to achieve crisp chips. Bake in oven until chips are crisp, about 25—35 minutes flipping chips half way through. Remove any chips that may have cooked quicker than the rest and lay on a paper towel and reserve to the side.

Sprinkle the warm chips with cayenne pepper before serving.