Preheat the oven to 200C and grease 2 baking trays - this recipe makes around 18 cookies.
Measure the butter and sugar into a bowl and beat together (creaming) until they are pale and fluffy, then add the egg yolk, reserving the egg white for later in the recipe, then mix well.
Add the flour and spices and fold in the currants to make a crumb-type mixture, then add the milk, a little at a time, to make a soft dough.
Roll the dough on a lightly floured surface so that it is around 1/4 inch thick, then use a 2-inch cutter to cut out your cookies from the dough and place on to your baking tray.
Place the cookies into the oven for 10 minutes and beat the egg white. After 10 minutes take the cookies out and brush with the beaten egg white and sprinkle with some sugar and return to the oven for a further 8 to 10 minutes.
Remove from the oven and place on a wire rack to cool.