Mary Berry, "Foolproof Cooking"
Named after the Hasselbacken restaurant in Stockholm where they originated. Also great sprinkled with cheese.
4 large baking potatoes (Maris Piper or King Edward) peeled & halved lengthways
15g butter
4 tbsp vegetble oil
sea salt
Preheat the oven to 180Cfan.
Gently boil in salted water for 6-8 minutes until parboiled - still firm in the middle. Drain and set aside until cool enough to handle.
Place the potatoes cut-side down on a chpping board between two wooden spoon handles. Slice two-thirds of the way down through each potato at 5mm intervals (the spoon handles will stop you cutting too far).
Meanwhile, put the butter and oil into a large roasting tin until piping hot. Add the potatoes cut-side down, and baste the tops.
Roast in the oven for 45-60 minutes (depending on size), basting halfway through, until tender, crisp and golden. Serve at once, sprinkled with sea salt.