I’m going to completely rework the missing method, based on how you’d normally do a shortbread, so please let me know if this doesn’t work…

Cream together the butter and sugar. Mix in the egg, beating well.

Sift and fold in the remaining ingredients. Roll out the dough to about half a centimetre thick.

You can either pre-cut your biscuits now and then refrigerate for 2 hours - but if the dough is a bit too buttery and melty, you can refrigerate it for 2 hours first, and then cut into biscuit shapes and arrange on a baking tray.

Bake for 12-15 minutes or until edges are just starting to brown, at 180°C. While still warm from the oven, sprinkle with additional caster sugar.