For the porcini soup, soak porcini mushrooms in water. Peel and dice shallots and potato. Drain the mushrooms (add the soaking water to the soup). Heat clarified butter and sauté mushrooms with shallot, deglaze with white wine.
Pour soup and add potatoes. Cook gently for about 25 min, then puree. Whisk the yolks with the whipped cream and add to the soup, which is no longer boiling. Season with salt, pepper and nutmeg.
Heat the butter and fry the bread cubes in it until crispy. Cut chives into fine rolls. Pour soup into soup bowls, sprinkle with bread cubes and chive rolls.