Preheat oven to 180°C (160°C fan-forced). Lightly grease and line 3 baking trays with baking paper.

Using an electric stand mixer, beat butter, sugar and zest together until light and fluffy. Carefully fold in flours, pistachios and cranberries, stirring with a wooden spoon until mixture is well combined.

Gently bring the mixture together as a smooth dough. On a lightly floured surface, roll dough into two 5cm wide logs (square or round), wrap in plastic wrap and chill in refrigerator for 30 minutes.

Using a sharp knife, cut 5mm thick slices and place on prepared baking trays. Bake in preheated oven for 15 minutes or until shortbread are golden. Let shortbread biscuits stand 5 minutes before lifting onto wire racks to cool.