Finely grind the dried mushrooms. Process together with flour, eggs, water and salt to make a spaetzle dough and cook. Firmer spaetzle are best suited for the sauce.
Finely chop the onions, cut the mushrooms into slices, fry both with butter in a large pan. Deglaze with cream and reduce a little. Add spaetzle to the mushroom sauce and season with instant stock, salt and pepper. Serve sprinkled with chopped parsley.