4 tablespoons extra virgin olive oil, or melted butter
1 teaspoon sea salt
1 tablespoon fresh rosemary, finely chopped
Preheat the oven to 375 F.
Place the potato between two cutting boards of equal thickness that come about 1/3 of the way up the potato. Make a series of 1/8-inch slices along each potato, slicing 2/3 of the way through. Run your knife down through the potato until it hits the bordering cutting boards and then stops, making 1/4-inch slices.
Place the potatoes on a rimmed baking sheet and brush liberally with olive oil. Sprinkle on sea salt and chopped rosemary.
Bake for 1 hour, until potatoes can be easily poked through with a fork and edges are golden and crisp.