For the chocolate cake, butter the cake pan and sprinkle with flaked almonds. Preheat oven to 170 degrees top/bottom heat.
Slowly heat 1 tablespoon of butter and the cooking chocolate in a bain-marie and allow to cool slightly. Separate the eggs. Cream the remaining butter, powdered sugar, salt and vanilla sugar together with the lukewarm chocolate, gradually add the egg yolks.
Whip the egg whites, add the granulated sugar and beat until creamy. Mix flour with grated almonds and baking powder and fold into the butter mixture alternately with the snow.
Pour the mixture into the prepared pan and bake in the preheated oven on the lowest rack for about 1 hour. Test with chopsticks. Let the pan stand for about 10 minutes, then turn out onto a wire rack and let the chocolate ring cake cool.