Preheat the oven to 300ºF (150ºC) and grease and line two 8-9 inch square pans.
Beat together the butter, sugar and extracts before adding in the flour and mixing until combined.
Beat until you have a stiff dough, do not worry if it appears dry, you can add a little water a tablespoon at a time until the dough comes together.
Divide the dough in hald then press each half into the prepared baking tins.
Prick the dough all over with a fork (allows the steam to escape prevent the bubbling up of the dough)
Place in the oven to bake for around 30 minutes until the top is starting to turn a very light golden brown.
Remove from the oven. Leave in the pans just for a couple of minutes before turning out onto a board.
Cut immediately into bars then place on a rack to cool completely.
Once cooled dip one end of the shortbread into the melted dark chocolate and place back onto the cooling rack. Sprinkle over the chopped pistachios.