Mix the eggs, sugar and cocoa together. Then melt the margarine and add it. Then add sour cream, flour and baking powder. Now stir everything into a smooth dough. Divide the dough between 2 trays. Bake at 180 ° C for about 15 minutes.
For the cream, whip the whipped cream, sugar and vanilla sugar until stiff. Finally, add the cream stiffener and sour cream to the cream. Spread the cream on one base and cover with the other base.