In a large bowl, beat eggs until light with an electric mixer on high speed. Reduce speed and add the anise essence and icing sugar. Continue beating at medium speed until well combined. Sift together the flour and baking powder; stir into the egg mixture, dough will be quite stiff.
Roll out dough to 6mm thickness. Imprint with a springerle board and cut apart. Place biscuits onto a baking tray and let rest uncovered overnight.
Preheat oven to 180 degrees C. Bake biscuits for 7 to 10 minutes.