Scrub the potatoes and cook, unpeeled, in boiling salted water until tender. Drain. When cool enough to touch, squish them flat using a coffee cup or ramekin. Don't let them explode, just flatten until the edges break a bit, but they are still in one piece. Toss in olive oil and season with salt and pepper.
Heat the oven to 400 degrees F/200 degrees C. Spread the potatoes on a baking sheet and bake until crisp outside and soft inside, about 40 minutes.