I found a very simple recipe via the BBC Food website. I doubled the recipe (to make sure we had enough to 'sample' of course) and drizzled dark chocolate over half of them and just a sprinkling of icing sugar on the rest.
These have a shortbread like texture, so quite crumbly and dry. They are especially nice with the chocolate drizzle. For the next batch I make I'll be half covering the cookies with chocolate. Can't wait for that experiment!