Grease a fat pan (approx. 32 x 39 cm; at least 3.5 cm high) and dust with flour. Roughly chop the chocolate. Melt 175 g butter at low heat.
Mix flour, cocoa, baking powder, brown sugar, 1 packet of vanilla sugar and 1 pinch of salt. Beat 5 eggs with the whisk of the hand mixer for about 7 minutes until foamy. Let melted butter run in and stir in.
Add the flour-sugar mixture in 2 portions and stir in briefly. Stir in crème fraiche briefly. Fold in chocolate. Spread on the fat pan.
Cream 125 g butter, sugar, 1 packet of vanilla sugar and 1 pinch of salt. Stir in 7 eggs individually. Stir in semolina. Stir in the quark in portions. Spread evenly on the brownie dough with a tablespoon.
Using a fork, pull spirally through the cheese mass and the brown rivet dough to create a marble pattern. Bake in the preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: level 2) for approx. 1 hour.
Allow to cool and dust with icing sugar.