Melt chocolate and butter in a saucepan and stir until smooth. Let the chocolate cool slightly.

While the chocolate cools, whisk sugar and eggs until light and airy.

Sift flour and cocoa powder into the egg mixture, along with salt. Fold gently until combined.

Carefully fold the cooled chocolate/butter mixture into the egg mixture.

Pour the batter into a 21 cm diameter tart pan lined with parchment paper.

Bake the chocolate cake on the bottom rack in a preheated oven at 170 degrees Celsius (338 degrees Fahrenheit) (conventional) for 30-35 minutes.

 

Mix crème fraîche, cream, and vanilla sugar in a bowl and whip it light and airy for 2-3 minutes with an electric whisk.

 

Quickly scald the blueberries and strawberries and cut them in halves.

Cut a thin slice of chocolate cake and serve with the whipped crème fraîche and berries.