N.B substituted cayenne for ¼ tsp mustard powder and ¼ tsp paprika.
Method
Chop the pistachio nuts until quite small.
Mix with all remaining ingredients and rub together until the mixture forms clumps. Press against the side of the bowl to bring it together.
Tip out onto the work surface and knead lightly. This won’t take long – the butter will start to melt quickly. Roll into a sausage shape about 18cm long and wrap in cling film. Chill in the freezer for 30 minutes or the fridge if longer.
Preheat the oven to 180c. Slice the chilled log into 5mm wide discs and spread out on a baking sheet. Bake for 13-15 minutes (usually 13) until just starting to go golden about the edges. Cool on a wire rack and store in an airtight container.