Adapted from Edd Kimber - Patisserie Made Simple Ingredients
275g plain flour 40g cocoa powder 3/4 teaspoon bicarbonate of soda 1/2 teaspoon flaked sea salt 200g unsalted butter, room temperature 50g caster sugar plus extra for rolling 200g light brown sugar 1/2 teaspoon vanilla extract 150g dark chocolate, chopped small Zest of 1 large orange 1 egg white Method Sift together the flour, cocoa, bicarbonate into a bowl. In the bowl of an electric mixer, beat the butter until soft and smooth. Add half of the orange zest, the sugars and vanilla and beat a further minute. The mixture will be crumbly (like sand). Mix in the chopped chocolate. Tip this out onto a clean work surface and press the mixture together to amalgamate it into one piece of dough. Working quickly but gently, form the dough into two sausage shapes of about 4cm thickness. Wrap the dough in cling film and chill for at least two hours, to allow it to firm up. You can also freeze it at this stage. When the chilling time is nearly over, pre-heat the oven to 180ºC and line two to three baking trays with greaseproof paper. Pour out some caster sugar onto a medium sized plate to cover it, along with the rest of the orange zest. Mix together to coat the zest. Unwrap the dough. Brush each sausage with egg white, then roll them in the orange zest sugar. Slice the dough into rounds of 1.5cm and lay on the trays. Bake around 10 minutes or until the tops are deeply crackled. Let cool completely on their trays before moving them onto a rack or plate. These make great gifts stacked up and wrapped in clear cellophane.