Collect together your equipment (see Recipe Notes below) and ingredients.

Preheat the oven to 160°C/325°F/Gas 3 (fan 140°C). You will also need an 18cm/7in loose-bottomed round cake tin. If your tin is prone to sticking, grease and line it, to be sure.

It is important that the butter is at room temperature and soft enough to beat. If it is a little hard, beat it with a whisk before adding the other ingredients. If it is already quite soft, you do not need to do this. For more information on softening butter, see here.

Weigh the caster sugar into a mixing bowl. Grate the lemon zest directly on top of the sugar and use your finger tips to rub the zest into the sugar.

Add the soft butter to the lemon sugar and beat until light and fluffy.

Weigh in half of the flour, the semolina and the salt. Roughly fold in with a spoon or spatula and quickly beat with an electric whisk. When incorporated, add the remaining flour and mix until it just comes together. Be careful not to over-mix at this stage.

Roughly shape into a flat round shape and place into the centre of the prepared tin. Use your fingers or a spoon to press it into the tin and then take a palette knife or flat sided jam jar to press/roll the top of the shortbread and ensure an even surface. Do not press too hard or the shortbread will be tough and hard.

Bake in a preheated oven for 30 – 40 minutes. It is cooked when it is very lightly browned. Take out of the oven and leave in the tin for ten minutes.

After 10 minutes, push the base with the shortbread on, out of the tin, onto a flat surface. Leave the shortbread on the base, immediately slice into biscuits and prick with a fork. Shake over some caster sugar and set aside for the shortbread to cool.