Bake the 9th of the challenge.
Shortbread really is as easy as 1, 2, 3! One part sugar, 2 parts butter to 3 parts flour (or flour and cocoa here), how perfectly simple is that?
However, do not do as I did. Having not made shortbread for a great many years, it was a bad idea to start again with a chocolate variety as it is very hard to judge when it is cooked, as you do not get the subtle colour change you get with other baking Mine was slightly underdone. The book warned the cocoa could scorch and not to let it get too brown – it was brown anyway before I started cooking.
As my oven temperature is spot on (I use an oven thermometer) and the cooking time was just over that in the book. Just goes to show that baking is about judgement as well as being scientific!