Could there possibly be anyone in the wide world who doesn't drool at the thought of jacket potatoes with really crisp, crunchy skins and fluffy, floury insides and something lovely melted into them? First you need to pre-heat the oven to gas mark 5, 375°F (190°C). To serve two people, wash two large Desirée potatoes weighing 8-10 oz each (225-275 g) and dry them very thoroughly with a cloth, then leave them aside to dry as much as possible. If you're using ready-washed potatoes you need not do this, as the high heat will purify them. Next, prick the skins a few times with a fork, then put a few drops of olive oil on each one and rub it all over the skin.
After that, rub in some crushed sea salt – this will draw out the moisture from the skin and, together with the oil, provide more crunchiness.
I used to put them in a hot oven but I've learnt over the years to get the crunch, they need to have slightly less heat and slightly longer cooking. So place the potatoes straight on to the centre shelf of the oven and let them bake for 1¾-2 hours depending on the size of the potatoes, or until the skins are really very crisp. Learn to use the time when you're out, so they can be ready when you come home, or go and do something else and forget about them till they're ready.
When you are ready to serve, slit each potato in half lengthways. Next, with a fork, fluff the floury insides, then add a generous amount of butter and watch it melt and disappear into the clouds of fluffiness. Add sea salt and crushed black pepper, then eat and savour it alone in all its humble, simple glory. Serve immediately because, after you remove jacket potatoes from the oven, they lose their crispness very quickly, so don't let them hang around.