Dark part: Melt chocolate and mix it with walnuts and powder sugar. Add orange zest and rum. Beat the egg whites separately until stiff and add it to the mixture. Put in the fridge for a little bit to cool down.
2
White part: Cook eggs beforehand to be hard boiled. Mix melted butter with sugar well. Mash egg yolks well with fork and add it to the mixture.
3
Lay aluminum foil or plastic wrap at the table and make a rectangle shape from dark part(about 2cm thin). Use plastic wrap to make a shape, since it would be sticky with hands. If it is too sticky put in the fridge to cool down first. When it's done, lay the white part on top of it. Using the plastic wrap roll it to the end, cover it from all sides and put to the fridge at least one hour. When ready for covering it with cocoa powder, slice and serve.