Preheat the oven at 175 degrees Celsius.
Mix the butter, sugar and the syrup together with an electrical mixer.
Add the flour, cacao powder, baking powder and vanilla sugar and mix well to a cookie dough.
Add 100 gr chocolate in the dough and mix.
Place a baking paper on a baking sheet.
Roll out the 3 dough pieces to 3 long rolls, place on the baking paper.
Press with the hand to get the dough a bit flat.
Place in the middle of the oven for 15 minutes.
Take out and sprinkle with the rest of the chocolate.
After a few minutes cut the dough in slices.
Let the cookies cool down before serving.