250g soft butter
140g icing sugar
1 tsp vanilla extract
1 large egg yolk
375g plain flour
Zest of a large lemon
Royal Icing
1 large egg white
170g icing sugar
​Juice of a large lemon
Beat together the butter and sifted icing sugar.
Beat in vanilla, egg yolk and zest.
Roll out on a lightly floured work surface to about 3mm thick. Cut out your shapes. Roll the left over pieces out again.
Pipe a border onto each biscuit and leave to harden. Thin down the icing to a runny consistency and spoon into the centre of the biscuit, then spread with a knife or by tipping the biscuit to fill the centre