1. In a large bowl, mix the prepared butter with the Demerara sugar.  Add the egg, mixing well.
2. Mix all the dry ingredients, and add to the egg mixture, mixing with a fork for a couple of minutes till the dough forms a softish ball.
   
3. Lay the dough on a sheet of baking parchment, form into a long rectangular sausage (depending on the desired shape of the biscuits).  Wrap firmly in the baking paper and refrigerate overnight.
   
4. Preheat oven to 180°.
   
5. Cut into thin 5-6mm slices and lay onto the baking tray lined with baking parchment.
6. Cook for 15mins till the surface is hard.  The speculoos will harden further as they cool.
   

These biscuits may be kept for up to a month in a sealed tin.

See the Banoffee recipe.