Heat the air fryer to 170°C.Rub oil all over the spuds, then sprinkle them with salt.Pop the potatoes into the air-fryer basket and cook for 20 minutes. Give them a good shake.Up the temperature to 200°C and cook for a further 10 minutes, until super-crispy on the outside and the flesh is tender.Remove the potatoes from the basket and cut each one in half. Scoop the flesh into a bowl, reserving the skins, and set aside.Separate out one quarter of the flesh into a different bowl (see below for what to do with the leftovers – waste no potato!) and mix it with the butter and almost all of the cheese (leave enough for sprinkling just before cooking).Season with salt and pepper, then spoon equal amounts of the cheesy potato back into the skins.Sprinkle the potato skins with the pancetta and remaining cheese and return them to the air fryer.Cook at 200ºC for 10 minutes, until the pancetta is cooked and the skins are crispy. Remove and garnish with the spring onion and crème fraîche (if using). Delicious served with a side salad.Recipe adapted from The Actually Delicious Air Fryer Cookbook by Poppy Cooks, published by Bloomsbury Publishing, 2023.