First stir in the sugar, vanilla sugar and salt with the butter until frothy. Add the eggs one by one and stir until the mixture is lighter. Add the cream. Mix the flour with the baking powder, sieve and fold into the egg mixture.
Now melt 150 g of the chocolate in a water bath. Divide the batter and mix the melted chocolate under half. Dice the remaining chocolate and mix into the light batter.
Grease a bundt pan or other cake pan with butter and sprinkle with flour / breadcrumbs. First add the light dough. Now pull the dark dough over it and then carefully pull spirals with a fork to create a marbling.
Bake the cake in a hot oven at 180 ° C for about 50-60 minutes.
If you want, you can dust the cake with powdered sugar after it has cooled down.