Wash the oranges thoroughly, place them whole and with their skin in a small pot, cover them with a little water and bring them to the boil covered. Simmer at low heat for about 2 hours. Remove the oranges with a skimmer, drain and let them cool down
Cut cooled oranges in half, remove seeds. Put the oranges into a high mixing bowl and puree them finely with a blender. Mix nuts, sugar, vanillin sugar, salt and baking powder
Place the eggs in a very large mixing bowl and whisk until creamy. Add orange puree and stir in. Then stir in the nut mixture in two portions
Pour the dough into a well greased, flour-spread pancake tin (approx. 2.75 litres). Smooth and bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for 60-70 minutes. Cover the cake with aluminium foil about 20 minutes before the end of the baking time. Remove the cake from the oven, place it on a cake rack and let it cool in the tin for about 40 minutes. Turn out of the tin and let it cool down
Coarsely chop the chocolate coating and melt it over a warm water bath. Leave to cool a little. Pour the melted chocolate coating over the cake and let it dry
Waiting time approx. 5 hours