Put sugar, brown sugar, vanilla sugar, and softened butter in a mixing bowl.

Beat it with a hand mixer until you have a soft and uniform mixture.

Beat in the egg - continue until the mixture is creamy and fluffy.

Mix flour, baking powder, baking soda, and salt together in a bowl.

Sift the flour mixture into the butter cream while you stir/beat at low speed. Do not overbeat the dough as you will get chewy, not crispy, cookies. 

Chop the chocolate into pieces the size of hazelnuts and add them to the dough.

Chill the dough for at least an hour or until the next day.

Get out your kitchen scale and weigh the dough into balls of 70 grams each.

Place the balls on a tray lined with baking paper. Ensure good spacing between each ball (place about 9 balls on each tray).

Bake your cookies in the middle of the oven at 180 degrees Celsius (356 degrees Fahrenheit) for about 16 minutes.

Cool the cookies on a wire rack - wait to pack them in cookie tins/bags until they are completely cold.