Start by separating 4 egg yolks from the whites, and beat the yolks with the sugar. Once you've obtained a smooth cream, add the oil and the lemon peel. Stir in the flour and then the yeast dissolved in milk. Work the mixture to obtain a dry, solid dough. Following this, separate part of the dough: one part is needed for making the various shapes of the cake, and the other for decorating it.
Once you've made the chosen shape, which can also be ring-shaped, press the eggs firmly into the dough and wrap them with strips of the dough previously kept apart, as a decoration. Bake for about 40 minutes at 150°C. In the meantime, whisk the egg whites into stiff peaks and stir in the icing sugar to form the icing, which is spread onto the cake once it is cooked. Sprinkle a little chocolate on top to finish.