Easter soup

While you boil the broth, whisk the 5 egg-yolks with a pinch of salt in a saucepan. Add the juice of half a lemon. When the broth boils, pour it over the eggs and stir continuously.
Continue to mix it all over the gas ring and let the soup thicken. Place the slices of bread on a serving plate and pour the broth over them; sprinkle the marjoram and the grated Parmesan cheese on top.