1. Preheat the oven to 450°. Pierce the potatoes all over with a fork. Arrange them on the oven rack and bake them for 1 3/4 to 2 hours, or until hard and crisp when tapped with a fork.
2. Using a serrated knife, split the potatoes without cutting them all the way through. Drizzle with olive oil, sprinkle with Maldon salt and serve.