Boil the unpeeled potatoes in salted water. Peel them and even out one side with a knife, carve out the other side.
Put 1 tsp butter in each hollowed out space.
Chop the bacon, pickles and mushrooms, stir them together and fill the potatoes with them.
Cover with grated cheese. Bake in a preheated 392°F (200 °C) oven until the cheese crisps.