Preheat the oven to 180C Gas Mark
4, grease a baking sheet.
Cream the butter, sugar and syrup.
Add the egg and vanilla essence,
then add the dry ingredients and mix well.
Place small spoonfuls of mixture
on the baking sheet and bake for 15-20 minutes, until lightly
browned.
Transfer to a wire rack to cool.
To make the filling, sift the
icing sugar and cocoa powder into a bowl and mix in the butter until
it forms a soft mixture, adding a little warm water, if necessary.
When the biscuits are cold,
sandwich them together with the filling.