• 6 fairly large potatoes
• 50 g (1¾ oz) butter
• 2 tablespoons olive oil
• a handful of sage leaves

Preheat your oven to 220°C (425°F/Gas 7). Peel the potatoes and cut them in half lengthways. Sit them, flat side down, on a chopping board. Using a small sharp knife, start at one end of the potato and cut down through the top, about a third of the way through. Make another cut about 1 mm away from the first, slightly on the diagonal towards the first cut, and break away the little piece of potato to make a slit. Continue along the potato, making slits about 5 mm (¼ inch) apart.

Handling the potatoes carefully so that they don’t break, arrange them in a baking dish. Add the butter and oil and season with salt and pepper. Scatter the sage leaves around and bake for 45 minutes – 1 hour, or until the potatoes are golden and crispy. Spoon a little of the buttery pan juices over the top from time to time and gently shuffle them so they don’t stick (but don’t touch them for the first 15 minutes or so or they will simply break.) Serve immediately.