Stuff the topping into toasted pitta breads with some shredded lettuce.
Prick the potatoes with a fork and sit them on a microwaveable plate. Rub the skins with the olive oil, and sprinkle with some sea salt if you like. Microwave on High for 8 mins until soft in the centre. Leave to cool while you prepare the topping.
Mix the soft cheese, celery, onion, apple and half of the walnuts, then season to taste. Cut the potatoes open, spoon on the topping and sprinkle with the remaining walnuts.