Melt the oil, ghee or butter and brush over the potatoes so the entire skin is covered. Generously season with sea salt then prick all over a few times. Bake at 420 for 45mins, until insides are soft and squishy. Carefully remove from the oven, slice lengthways, scoop out the insides (being careful not to rip the skin) and put the potato in a bowl. Put the empty shells back into the oven to crisp up further while you are mashing. Add the avocado to the potato, season well and mash vigorously. Stir in the chicken and green onions. Transfer the mash back into the potato skins and return to the oven for ten more minutes until they brown.