Preheat the oven to 160°C (315°F/Gas 2–3). Using your hands, rub the butter and flour together to form coarse crumbs. Add the squid ink and spice mix and mix until a dough forms. Place between baking paper and roll out to 5 mm (¼ inch) thick. Place on a baking tray, remove the top sheet of paper and bake for 15 minutes or until crisp. Cool on the tray. Crush into small pieces using a mortar and pestle and fold through the purée. Set aside.
These can be made 1 day in advance and stored in an airtight container.