Mix all ingredients in a food processor until completely smooth

Spread mixture out in a circle on a piece of baking paper on top of a baking sheet.

Use a knife or a pizza cutter to mark off lines to divide the circle into eight pieces. Use a fork to 'petticoat' the outside edge all round and to make marks on the shortbread.

Bake for 15-18 minutes at 180 C/350 F/ Gas mark 4. You may need to turn it round occasionally if the edges are browning in places. If the edges are browning too quickly, drop the temperature slightly. The centre will look 'dry' when it is cooked.

You may need to just carefully go over the dividing lines once out of the oven.

Remove baking paper to a wire rack carefully.

Allow to cool for as long as possible before cutting. This will be quite crumbly and a fair bit softer than traditional shortbread.

This does not keep for long as it gets soft when stored, but it will keep best in the fridge or a biscuit tin in a cool dry place.