For the chocolate cake, beat the softened butter and sugar with the whisk of a food processor to a fine cream. The sugar should have dissolved completely.
Add the eggs and the flour mixed with baking powder and cocoa and mix everything together. Add enough milk so that the dough flows from the spoon with difficulty tearing.
Pour the dough into a deep baking tray or a large shallow loaf pan and bake in the oven at 170 °C convection oven for about 30 minutes. (Test with a stick). Allow the finished cake to cool and cut into pieces (approx. 16).