Set the oven to 200C. Prick the potatoes all over with a fork, rubbing in olive oil and salt and bake for 30 minutes. Meanwhile, fry the bacon, adding the leaks and stir over a moderate heat until cooked.
Once the potatoes have softened, remove from the oven, cool and split in half to scoop out the centre. Lay the empty skins cut side up and back onto the baking tray.
Mix the potato filling with the leek and bacon, adding butter, creme fraiche and the Black Truffle Oil. Adjust the seasoning with salt and fill the potato skins with the mixture. Finally, scatter the filled potatoes with cheese and pop under the grill for 5-10 minutes or until the cheese has melted. Delicious!