Preheat the oven to 180 degrees C, 360 F or Gas mark 4
Cream the butter and sugar together until creamy and fluffy.
Add the plain flour and the lemon zest and mix lightly until it just comes together.
Pull together into a dough and then divide into 20 small balls.
Place the balls onto two baking trays making sure to spread them apart.
Dip a fork in a cup of water and use the fork to flatten each cookie.
Bake for 15 minutes until they turn a pale golden colour.
Cool on a wire rack.