Ingredients

• 100g/3½oz unsalted butter
• softened
• 75g/2¾oz caster sugar
• plus extra for dusting
• 1 free-range egg
• separated
• 1 small unwaxed lemon
• finely grated zest only
• 200g/7oz plain flour
• plus extra for dusting
• 50g/1¾oz currants
• 1–2 tbsp milk

Directions

• Preheat the oven 200C/180C Fan/Gas 6. Line three baking trays with baking paper.
• Put the butter and sugar in a bowl and beat until well combined and fluffy. Add the egg yolk and lemon zest. Sift in the flour and mix well. Stir in the currants and enough milk to make a fairly soft dough.
• Knead the dough on a floured work surface and
• using a rolling pin
• roll out the dough until 5mm/¼in thick. Using a 6cm/2½in fluted cutter
• cut out 24 rounds. Transfer to the baking trays using a palette knife and bake for 8 minutes.
• Lightly beat the egg white using a fork.
• Remove the biscuits from the oven and brush the tops with the beaten egg white. Sprinkle over caster sugar and return to the oven for 5 minutes
• or until pale golden-brown and cooked though. Leave to cool on the trays for a few minutes
• then carefully lift onto a wire rack to cool completely.