Clementine, pistachio & white chocolate biscuits

1. First, make the candied clementine. Use a vegetable peeler to pare the zest (leaving the white pith) from the clementines; slice into thin strips. Put 50g caster sugar in a small pan with 4 tbsp water and the juice of 1 clementine. Stir over a low heat to dissolve the sugar. Add the zest strips, bring to the boil and simmer for 5 minutes, until the zest darkens and the liquid turns syrupy. Drain any excess syrup from the zest then spread it out on baking parchment to cool. 

2. Using a wooden spoon, beat the butter and the remaining 125g caster sugar together in a mixing bowl until light and fluffy. Beat in the egg, salt and vanilla extract. Sift over the flours and mix to half-combine. Add the white chocolate, pistachios and ½ the candied clementine zest, kneading lightly to form a dough. Halve and shape into 2 plump sausages, wrapping each tightly in baking parchment like a cracker. Chill for at least 1 hour (or up to 2 days). 

3. When ready to bake, preheat the oven to 180˚C, gas mark 4. Line 2 large baking trays with baking parchment. Spread the demerara sugar out on a plate. Unwrap the biscuit dough and firmly roll each cylinder in the sugar to coat completely. Use a serrated knife to slice each cylinder into 12 rounds (just under 1cm thick). Space the biscuits out on the baking trays and bake for about 14-16 minutes, until pale golden. Cool the biscuits on the trays for a few minutes, then scatter the surfaces with the remaining candied clementine zest. Transfer to a wire rack to cool completely.