Pre heat oven to 160c and line 2 baking sheets with baking paper.
In a stand mixer or bowl for a hand mixer, place in your butter and icing sugar.
Beat the butter and sugar until light and creamy.
Add in your cocoa powder, salt and flour and beat until everything is well combined and a dough forms.
Remove the dough onto a piece of baking paper or floured surface and roll to ½cm (less than ¼ inch) thick.
Use a 5cm round cutter (or cutter of your choice) and cut the cookies.
Place onto baking sheets and place in the oven for 15 - 17 minutes.
Remove from the oven and set aside to cool.
Place your white chocolate in the microwave for 20 seconds at a time until it is mostly melted.
Give the white chocolate a good mix till it is fully melted and add in the pistachio spread.
Mix well and put aside to set.
When the cookies are cool, place the ganache into a piping bag (if your ganache is too runny you can place in the fridge for a few minutes, if it is too firm place it in the microwave for a few minutes). Pipe a mound into the centre of half the cookies. Place the other half cookies on top of each filled cookie.
Drizzle with left over ganache.
