For the dark dough, melt the butter and the cooking chocolate together in a saucepan over low heat.
Mix eggs, sugar and vanilla sugar until the mixture is really thick. Mix the flour, baking powder, cocoa powder and salt together. Add the chocolate butter, milk and flour mixture in small quantities to the egg mixture in the mixer and mix everything together well.
Set aside about 6 tablespoons of dough for marbling and place the remaining dough on a baking sheet lined with baking paper.
For the light dough, mix the cream cheese well with sugar, eggs and vanilla sugar.
Spread the cream cheese mixture on the chocolate dough and make a pattern with the chocolate dough set aside.