Add the 6 tbsps of the pistachio spread onto a baking paper lined tray in individual dollops. You can either use a spoon to do this, or put the pistachio spread into a piping bag and pipe the dollops. Leave this in your freezer.
In a large bowl, add the cold butter, both sugars and vanilla, beat together for 5 minutes. Add the eggs and egg yolk and beat to combine.
In a separate bowl, mix together the flour, corn flour, baking powder and salt. Add this into the other bowl, along with the chopped chocolate and pistachios. Mix everything together until you can no longer see any flour.
Divide this dough into 6 pieces, each piece around 150g.
Get one of the cookie dough pieces, flatten it out, then add one piece of the frozen pistachio spread into the centre. Roll this into a ball, making sure the pistachio spread is fully covered.
Repeat this with the rest of the cookie dough, then place these onto a tray and freeze for an hour.
About 10 minutes before you're ready to bake them, pre-heat your oven to 220°C.
Place your cookie dough balls on a large baking paper lined tray, making sure to leave gaps between them so they have room to spread.
Bake the cookies for around 20-22 minutes.
Leave your cookies to cool on the tray for about 10-15 minutes before trying to pick them up, they will be too soft at first. But then enjoy!
