1. Heat your oven to 140°C (or 160°C for a non-fan oven, which is a better option for this recipe if available). Line a baking tray with baking parchment or silicone paper – I suggest you do this even if your tray is non-stick.
2. Mix the flour, baking powder and sugar together in a bowl. Stir in the beaten eggs, a little at a time, making sure each addition is incorporated before adding the next. Continue until you have a firm dough; it may not be necessary to add all of the egg. The dough shouldn’t be at all sticky. If you are making chocolate biscotti, add the extra flour and be careful with the amount of egg you add (as the melted chocolate will also add to the stickiness of the mixture).
3. Now it’s time to add your chosen flavouring (the quantity of each of these is sufficient to flavour the whole batch of dough).
a. For the pistachio and cranberry biscotti, roughly chop the pistachio nuts and dried cranberries and add them to the biscotti dough with the lemon zest. Mix the flavouring ingredients in with your hands until they are evenly incorporated.
b. For the hazelnut and date biscotti, roughly chop the nuts, keeping them chunky (some can remain whole). Roughly chop the dates and add to the biscotti dough with the nuts and lemon zest. Mix in with your hands until well combined.
c. For the chocolate, almond and orange biscotti, melt the chocolate in a bowl over hot water, then cool until tepid. Roughly chop the almonds. Add the melted chocolate to the biscotti dough and stir until evenly incorporated. Bring the mixture together to form a firm dough. Add the almonds, chocolate chips, orange zest and vanilla extract. Mix these ingredients in with your hands until well combined.
4. Once you have added your flavourings, turn the biscotti dough out onto a floured surface and knead gently, then divide in half.
5. Roll each piece of dough into a long log, about 4cm in diameter. Place both logs on your lined baking tray, spacing them at least 5cm apart as the mixture will spread a bit. Bake in the oven for 30-35 minutes.
6. Leave the logs to cool on the tray for 10 minutes to allow the dough to firm up slightly, then transfer to a board. Cut the logs, on the diagonal, into 2-3cm thick slices.
7. Place the slices, cut side up, on the baking tray. Return to the oven for 20-30 minutes, or until the biscotti are dry through to the centre, turning them over halfway through. Transfer to a wire rack and leave to cool completely. These biscotti keep well in an airtight container.