With an electric mixer, cream butter and icing sugar together until pale and fluffy. Add the vanilla extra and beat for a few seconds.
Sift the flour and cornflour together over the butter mixture and mix until smooth.
Spoon the mixture into a piping bag fitted with a large star-shaped piping nozzle. Pipe into the required shapes on a baking tray lined with parchment paper. Space the shapes well apart.
Bake the cookies in preheated oven at 180degC for 12 minutes or until they are a pale golden colour. Leave for a few minutes on the baking tray to firm up slightly before transferring to wire rack to cook.