Cover the rolled barley with cold water and let it soak for several hours. The dried porcini mushrooms also, but only about 1/2 hour. Finely chop the shallots, melt the butter in a large soup pot and sauté the shallots until they are translucent. Strain the rolled barley, but do not discard the soaking water. Add the rolled barley to the pot, pour in the whipping cream and cook over a low heat. Meanwhile, strain the mushrooms and keep the soaking water as well. Add the mushrooms to the barley and steam briefly. Then add the remaining barley and mushroom water and beef broth as needed and cook on low heat for about 3/4 hour until the barley is tender. At the end, add the egg yolks to the soup, but do not let it boil anymore and serve hot.