1. Sieve the flour, cocoa and baking powder together.
2. Cream the margarine and sugar very well until light and creamy.
3. Add the vanilla essence and golden syrup and beat very well.
4. Add the flour mixture and mix very well.
5. On a small sheet of grease proof paper, sprinkle sugar. Roll a small portion of the dough over the paper. Sprinkle granulated sugar over the rolled dough.
6. Stamp out biscuits with a biscuit cutter. Prick with a fork all over the biscuits.
7. Arrange these biscuits over a well-greased baking tin.
8. Bake in a moderate oven at 350 °F for 15 to 20 minutes.
9. Cool the biscuits.
10. Sandwich the biscuits with butter icing.