Preheat the oven to 325 F / 160°C / Gas mark 3.

Place the flour, cornflour, almonds, and salt in a food processor and add the butter. Blitz together for a couple of minutes then add the sugar. Blend until the mixture looks like fine breadcrumbs.

Then add water and almond essence, using the pulse setting combine the ingredients into a paste stopping as soon as the mixture binds together as to not over work the dough.

Roll out a sheet of cling film on to your work surface and spoon on the paste in a line. Roll tightly in aluminium foil to make a sausage shaped parcel, tying the ends. Refrigerate for at least an hour until hard.

Take out from the refrigerator and slice using a sharp knife in to one quarter of inch thick slices and place on a baking tray covered with either baking parchment or a silicon mat.

Sprinkle with some extra caster sugar and bake in the preheated oven for 10–15 minutes or until lightly golden.