Let the butter in room temperature until it is soft enough to work with a fork. Mix the butter together with the sugar with a fork.
Preheat the oven at 180 degrees Celsius.
Add the eggs in the butter one by one, while stirring with the fork.
Gradually add the flour and the baking powder in the mixture.
Chop the chocolate in small pieces, and add it in the mixture.
Butter a baking form and pour in the mixture.
Place the cake in the oven for approx forty minutes. Take out the cake and let it cool down before serving.