Mix the flour with the baking powder and salt and knead into a dough with the sugar and butter mixture and the remaining biscuit ingredients.
Shape the dough into a ball and wrap in cling film. Then place in the fridge for at least 1 hour.
Preheat the oven to 180° convection oven. Line a baking tray with baking paper.
Roll out the chilled dough. The thickness of the biscuits is indicated by the chopped pistachios. Once you hit the pistachios when rolling out, you don't need to roll out any further.
Cut out the dough and bake the biscuits for approx. 10 - 12 minutes. Then leave the biscuits to cool.
Melt the chocolate over a bain-marie and then spread over the cooled biscuits with a fork/spoon. Of course, you can also dip the biscuits in the chocolate or cover them completely with it - depending on what you need, you may need a little more chocolate.
Sprinkle the chopped pistachios directly onto the still warm chocolate. Then leave the biscuits to stand until the chocolate has cooled.