Chocolate-dipped spiced biscotti
Preheat the oven to 160°C, 325°F, Gas 3. Whisk the egg and the caster sugar for a few minutes using an electric mixer, until the mixture is pale and mousse-like, then fold in the plain flour, the baking powder, the orange zest, the pinch of salt and the ground cinnamon, then mix well.
With floured hands, on a floured surface, shape the dough into a log shape about 4cm x 28cm (1½in x 11in). Put the log on a parchment-lined baking tray. Brush the log with the milk and sprinkle with a little caster sugar, then bake in the oven for 25 minutes, until it's just set and pale golden. Remove the tray from the oven and allow the log to cool for 5 minutes.
Using a bread knife, cut the log at an angle, into roughly 20 slices that are about 1cm thick. Put these slices flat on the tray and put in the oven. Cook the biscotti for 4-5 minutes on each side, until they are pale golden and dry. Cool on a wire rack.
Place the dark chocolate in a heatproof bowl over a saucepan of simmering water. When the chocolate has melted, dip the biscotti slices about halfway into the chocolate. Allow any excess to drip off, and place on a plate to cool and set. The biscotti will keep well for about three weeks if they are stored in an airtight container.