75g caster sugar
2 tsp finely grated orange zest
125g plain flour, plus more for rolling
½ tsp baking powder
freshly grated nutmeg
75g shelled pistachio nuts
50g dried cranberries
Heat oven to 180C/160C fan/gas 4. Whisk the egg and sugar until pale and moussy: the mixture should leave a ribbon-like trail when you lift the beater. Beat in the orange zest, then slowly fold in the flour, baking powder and a good grating of nutmeg. Fold in the pistachios and cranberries.
Flour your work surface well, and you may find it helpful to dust your hands lightly with flour, too, as the dough is quite sticky. Now form the dough into a flattish, oval ciabatta-like loaf, about 25 x 5cm, tapering the ends slightly.
Lay the biscotti loaf onto a piece of baking parchment on a baking sheet and cook for 25-30 mins or until it is a pale brown colour. It may help to rotate the baking sheet halfway through the cooking time, as the base can brown quickly; this reduces the risk of the base scorching at one end.
Transfer to a wire rack and leave for 5 mins to harden slightly; then, using a bread knife or similar stout serrated-edged knife, cut the baked loaf diagonally into fingers about 1cm thick. Put these back onto the sheet covered with baking parchment, and cook again for another 10 mins. Then turn the biscotti over and cook for yet another 5 mins. Let the golden brown biscotti cool on a rack, then store them in an airtight container.