Speculoos is a traditional Dutch shortcrust biscuit, traditionally baked on or just before St Nicholas' feast in the Netherlands (December 5), Belgium (December 6) they are thin, very crunchy, slightly browned and, most significantly, have some image or figure (often from the traditional stories about St. Nicholas) stamped on the front side before baking; the back is flat. Yummy they are available in the supermarkets in the section you find international food. In The Netherlands you can buy the stamps I guess they are available in Australia too?