Cook potatoes, peel and cut in halves length. Carve like boats. Mushrooms cut into slices and sauté in a part of the butter. Hollowed part of the potatoes are pressed and added to the mushrooms with egg. The mixture is seasoned with salt, pepper and parsley. The potatoes are brushed with butter on the inside and fill with stuffing. On each potato put a slice of processed cheese and roast in a preheated oven.