Method

• 1.
  Combine flours with a pinch of salt flakes in a bowl. Place butter, caster sugar and vanilla in a stand mixer fitted with the paddle attachment and beat on mediumlow speed for 1 minute or until smooth. Add dry ingredients and cacao nibs, and beat for about 1 minute or until dough just comes together in ‘sandy’ clumps.

• 2.
  Turn out dough onto a clean work surface. Shape into a log about 20cm long and 5cm wide (it may take a little work to bind, but it will get there). Enclose in plastic wrap and chill for 1 hour 30 minutes or until just firm. Remove from refrigerator and bring to room temperature. Preheat oven to 170°C. Line 2 large trays with baking paper. Stir demerara sugar and espresso powder together in a bowl. Cover work surface with a sheet of plastic wrap and spinkle over espresso sugar. Unwrap the dough, brush with eggwhite and roll in the espresso sugar to completely coat.
• 3.
  Using a warmed sharp knife, carefully slice dough into rounds about 1.5-2cm thick. Divide between prepared trays and bake for 13-15 minutes or until light golden brown around the edges. Rotate trays halfway through cooking to ensure an even colour. Cool for 10 minutes on trays, then transfer to a wire rack to cool completely. Store, in an airtight container, for up to 5 days.