Melt 200 g of the dark chocolate with 120 g of butter, stir and let cool down a little. Crush the remaining chocolate (it is best to crumble it in a freezer bag). Mix the flour with the baking powder and salt. Mix eggs, sugar and vanilla sugar until frothy and add the lukewarm chocolate mixture. Gradually sift in the flour mixture and carefully stir everything into a dough. Now fold in the remaining chocolate chips. You can also choose to have a handful of chopped walnuts here.
Grease a brownies baking pan (approx. 23 x 23 cm) with the remaining butter, add the dough and smooth it out. Then place in the oven preheated to 180 degrees for 20-25 minutes with a wire rack on the middle rack. The right time has to be found here so that the brownies are still nice and moist and crunchy on the inside. It is best to stick with it for 20 minutes or more. When the edge is nice and deep dark brown, they should be done.
After cooling, either leave pure or spread with whole milk couverture and decorate with diagonal stripes with white couverture. Cut into 16 squares, or 32 smaller squares.
Very suitable for freezing. After freezing, let thaw briefly and serve with a scoop of vanilla ice cream.