Preheat the oven to 180°C (160°CFan) and line a baking tray with baking parchment and leave to one side
In a bowl, cream together the butter and both sugars until pale in colour and fluffy.
Add in the egg, flour, vanilla, baking powder, bicarbonate of soda and cornflour and mix until completely combined and a dough begins to form.
Add in the chocolate chips and Pistachios and mix again until they are evenly distributed.
Weigh your cookie dough into balls of around 100g.
Press the dough in the palm of your hand until it is flat, add one of your frozen pistachio spread blobs and wrap the cookie dough around it.
Bake for 13-15 minutes or until they are golden brown around the edges.
Remove from the oven and leave to cool fully on the baking tray.