Preheat the oven to 160ºC
Line the baking trays with parchment paper
Fit the K beater to the machine
Add Ingredients 1 (butter, sugar) into the Mixer bowl
Attach the Mixer bowl to the machine and fit the splash guard
Mix on speed 3 for 1 minute
Scrape down the sides of the bowl with a spatula
Add the first item of Ingredients 2 (egg yolk) into the Mixer bowl
Mix on speed 3 for 20 seconds
Add the remaining Ingredients 2 (flour, mixed spice, salt, currants, candied peel, milk) into the Mixer bowl
Mix on speed 1 for 30-40 seconds until a stiff dough formed
Transfer the dough to a lightly floured work surface
Roll out the dough into a circle
Using a round, fluted cutter, cut out biscuits
Transfer the biscuits to the prepared baking trays
Bake at 160ºC for about 10 minutes
Remove the baking trays from the oven
Brush the biscuits with the first item of Ingredients 3 (egg white)
Sprinkle with the second item of Ingredients 3 (caster sugar)
Bake at 160ºC for 5-10 minutes until light golden brown
Remove the biscuits from the oven
Turn out onto a wire rack
Let cool completely