Sift the cocoa with the flour for the layer. Beat the egg yolks with the sugar to a fluffy cream, gradually add the water and dry ingredients and finally mix with the whites that have been beaten to snow. Bake the layer in a cake form with baking paper. Once it cools, cut it into 3 separate layers.
Boil the syrup and soak the layers with it. Stick them together with the buttercream but also be sure to set some of it aside for smearing and garnishing. To prepare the buttercream, beat the butter with the sugar and eggs, by stirring in a water bath and adding and stirring with the crumbled chocolate.
For the glaze, melt the sugar, water and glucose with the cocoa in a container on the stove.
Smear marmalade on top of the assembled cake. Glaze it with the warm fondant and let it cool well. Smear the sides with the set aside cream and if desired decorate with walnuts and chocolate sprinkles.