Lemon shortbread biscuits
Put the flour in a bowl with the caster sugar and the finely grated lemon zest. Mix, then rub in the cubes of butter and squeeze the mixture in your hands to bring it together to form a dough. Alternatively, you could bring these ingredients together very briefly in a food processor.
Roll the dough out until it is 1cm (ªin) thick, keeping it in a square or a rectangle. Cut it into rounds, fingers, or any shape you prefer! Place the biscuits on a baking tray (there's no need to grease it or line it) and bake them for 6-8 minutes until they are a light golden colour. Take the tray out of the oven and let it stand for two minutes before transferring the biscuits to a wire rack to cool. Sprinkle them with a little icing sugar to serve, if you are using it.