I think of these Swedish roast potatoes as being rather like sauteed potatoes on the stem: each one is cut into thin slices across almost right through, but not quite, and then roasted in buttery oil; as they cook, the potatoes fan out, like slightly fleshy crisps with their bottoms still attached.
Traditionally, maincrop potatoes are used, but I love these made with new potatoes, too; in which case, Charlotte or Ratte, which are waxy-fleshed and taperingly oval in shape, are best. If you're using maincrop potatoes, avoid those huge floury monsters; moderately proportioned Cara potatoes, or similar, would be just fine for the job. If you want to peel the potatoes, do, but I find it isn't necessary. And if I buy those shiny, pebbly supermarket ones, I don't even scrub them.
Recipe posted by Nigella