Cream margarine and sugar together until soft and fluffy. Beat in the egg, then add the flour gradually until all is combined into the mixture. Grease three baking sheets, then using a large star tube, pipe the mixture on the trays, making 36 biscuit shapes. Bake in a hot oven, 400?F, for 10-15 minutes, keeping a close eye on them to see that they do not brown too quickly. Cool on wire racks, then dip half of the biscuits into melted chocolate to half their width. Wait until the chocolate has hardened, then sandwich together each chocolate-coated half with a plain half, using buttercream made by creaming together the icing sugar and butter.