I played around with different shortbreads last Christmas, and in the end my favourite (and easiest to handle) was the red and green shortbread from the Festive Flavours booklet. I dont always use the cranberries and pistachios, but use that recipe as a base and add whatever else I want. Last year I added powdered lemon myrtle to make lemon myrtle shortbread, and they were very nice too.