Wikipedia
Speculaas (Dutch: Speculaas , French: spéculoos, German: Spekulatius) is a type of spiced shortcrust biscuit, traditionally baked for consumption on or just before St Nicholas' feast in the Netherlands (December 5), Belgium (December 6), and around Christmas in the western and southern parts of Germany. Speculaas are thin, very crunchy, caramelized, 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.
Speculaas dough does not rise much. Dutch and Belgian versions are baked with light brown (sometimes beet) sugar and baking powder. German uses baker's ammonia as leavening agent. Indian, Indonesian, and Mediterranean spices used in speculaas are cinnamon, nutmeg, cloves, ginger, cardamom and white pepper; these were common in the 1400-1500s due to the Dutch East Indies spice trade. Family recipes may also include other small amounts of spices like anise, etc. Traditionally, speculaas were made from Frisian flour and spices. The name speculoos was coined for Belgian wheat flour cookies with hardly any spices. Today most speculaas versions are made from white (wheat) flour, brown sugar, butter and spices. Some varieties use some almond flour and have slivered almonds embedded in the bottom.
The dough is prepared by beating butter, sugar and spices and combining them. The flour and leavening agent are mixed separately and then added. Bakers are careful not to overwork the dough, so it will rise slightly. The dough is stored in a cool place overnight to give the spices time to permeate the dough and add extra flavor.