For the cake wash and clean the strawberries. Put about 25 nice fruits aside, cut the rest into cubes. Cream 300 g butter, 300 g sugar and vanilla sugar with the whisk of the mixer. Stir in the eggs one by one. Mix flour and baking powder, stir into the dough.
Spread half the dough in a greased fat pan (approx. 32 x 39 cm). Mix the rest of the dough with cocoa and 2 tbsp. milk. Spread on the light-coloured dough. Spread the strawberry cubes on the dough. Bake the cake in a preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer) for approx. 30 minutes. Let it cool down.
For the cream, mix pudding powder with 75 g sugar and 100 ml milk. Bring 650 ml milk to the boil. Stir in the pudding powder and simmer for about 1 minute. Pour the pudding into a bowl. Place foil directly on the surface. Let it cool down.
Whisk 375 g butter with the whisks of the mixer until white and creamy. Stir the warm pudding through and stir into the butter by the spoonful. Approx. 2⁄3 Pour the butter cream on the pastry base and smooth it down. Leave to set in a cool place for about 4 hours.
Divide the chocolate into pieces and melt with 25 g butter in a hot water bath. Cut the strawberries in half crosswise. Spread the chocolate on the cake. Place the lower strawberry halves on the cake at even intervals. Pour the rest of the buttercream into a piping bag with a perforated spout and spray onto the strawberry bases. Place the upper strawberry halves on top and press down slightly. Refrigerate again for about 30 minutes until the chocolate icing is firm.