Ingredients
Method
1.Preheat oven to 150°C. Grease two oven trays. Beat butter and sugar in a small bowl with an electric mixer until combined.
2.Sift flours and cocoa together. Add vanilla extract and ground cardamom to sifted flours and cocoa. Add large spoonfuls of cocoa flour mixture to butter mixture, beating after each addition. Add vanilla extract and ground cardamom with the cocoa flour mixture. Press ingredients together gently; knead on a lightly floured surface until smooth.
3.Divide dough into two portions. Shape portions into 18cm (71/4in) rounds.
4.Place rounds on trays; mark into wedges, then prick with a fork. Pinch a decorative edge with floured fingers.
5.Brush tops of shortbread rounds with beaten egg yolk; sprinkle with pistachios and extra sugar.
6.Bake shortbread for 30 minutes. Leave shortbread on trays for 10 minutes before transferring to wire racks to cool. Cut when cold. Recipe can be made a month ahead; store in an airtight container.
