Preheat your oven to 150c/130c fan oven

In a bowl add the flour and butter and rub together to form fine crumbs

Stir in the sugar, lemon extract and lemon zest then work the mixture together until it forms a ball.

Tip out on to a floured work surface and knead a little until the dough is smooth.

On a floured surface roll out the dough into a 18cm round. Pinch the edges to make a fluted pattern and carefully transfer to a baking tray.

Score the dough into 8 slices and prick all over with a fork. Bake in the oven for 30-35 minutes. The shortbread will still be pale.

While it is still warm sprinkle the surface with sugar and cut into 8 slices. Leave it to cool completely on the baking tray before eating.