For the limoncello, heat the sugar and 75ml/5 tbsp water in a saucepan over a medium heat. Stir to dissolve the sugar.
Bring the mixture up to the boil, then simmer briskly for 3-4 minutes until the bubbles look syrupy. Remove from the heat and leave to cool.
Add the lemon zest and juice to the syrup while it is still slightly warm. Then add the eau-de-vie or vodka.
Pour the limoncello into a sterilised bottle or jars and seal. Leave in a cool, dark place for 24 hours, shaking occasionally, then strain into a clean bottle.
Put in the freezer for several hours before serving. The liqueur is best served in frozen shot glasses.
Method for biscotti, preheat the oven to 180C/350F/Gas 4 and line a baking tray with parchment.
Mix the flour, sugar and baking powder together in a large bowl.
Add half the beaten eggs and mix well, then add half of what’s left and mix again.
Now add the last quarter a little bit at a time until the dough takes shape but isn’t too wet (you may not need to use all the eggs).
Add the dried fruit and lemon zest and mix well.
Divide the dough in half, and each half into a sausage shape and place on the baking tray, leaving at least a 6cm/2½in gap between them.
Lightly flatten the ‘sausages’, then bake for 20-30 minutes until golden brown.
Remove from the oven and leave for 10 minutes to cool and firm up.
Turn the oven down to 150C/300F/Gas 2.
Once cooled move the cooked biscotti dough onto a cutting board. Using a serrated knife, cut the biscotti on an angle into 5mm/¼in slices.
Lay the slices on the baking tray. Return to the oven and cook for eight minutes, then turn the slices over and cook for a further 10-15 minutes or until pale golden brown.
Remove from the oven and cool the biscotti on wire racks.
To serve, pile the biscotti onto a plate and serve with a shot of limoncello.