Cook the potatoes in a pan of boiling salted water for 15 mins, or until cooked through but not falling apart. Drain well. Drizzle 1 1/2 tbsp oil into a shallow roasting tin or baking tray (about 30 x 20cm – a Swiss roll tin works well). Tip the potatoes into the tin and toss in the oil. Squash the potatoes down using a potato masher or fork – the smashed potatoes should fill the tray and be joined at the edges like jigsaw pieces. Will keep chilled for up to a day.

Heat the oven to 190C/170C fan/ gas 5. Drizzle the potatoes with the remaining oil and season with sea salt. Bake for 40 mins until deeply golden and crunchy.