For the spaetzle, use the first 5 ingredients to make a tough dough. Scrape the spaetzle from the board into boiling salted water, cook. Drain.
In the meantime, steam the mushroom mixture in the margarine. Mix the stock cube with the water. Spread the flour or cornstarch over the mushrooms and sauté briefly. Pour the broth and the cream or milk over it and cook for about 5 minutes.
Mix in the spaetzle and let everything continue to cook until the liquid is very thick.