Method

• 1.
  To make the shortbread, in a stand mixer fitted with the paddle attachment, beat the butter and icing sugar for 6-8 minutes, until soft and pale. Add flour, egg yolks and a pinch of salt flakes and beat to form a soft dough. Set aside half the dough. Add spices to bowl and beat until just combined. Turn dough onto a flat surface and shape into a disc. Cover with plastic wrap and chill for 30 minutes. Place remaining dough in the bowl with the chocolate and cocoa and beat until combined. Turn dough onto a flat surface and shape into a disc. Cover with plastic wrap and chill for 30 minutes.
• 2.
  Roll each dough until a 33cm x 24cm rectangle. Lay one rectangle of dough on top of the other, making sure the edges align, and press down to adhere. With the shortest edge towards you, fold into three like a letter. Turn 90 degrees so the shortest edge is towards you, then fold over like you’re closing a book. Press down to adhere. Cut in half lengthways and stack one on top of the other to form a high, narrow squared log with sharp 90-degree edges (if your edges aren’t quite right, press on each side to shape edges). Wrap in plastic wrap and chill to firm up.
• 3.
  Preheat oven to 170°C/150°C fan-forced. Line 2 baking trays with baking paper. Cut log into 0.5cm slices and arrange on prepared trays. Bake for 14 minutes, or until pale and matte-looking. Cool on trays.