Preheat oven to 160oC/325oF. Line baking sheet or flat oven tray with parchment paper.
Beat butter, vanilla and sifted icing sugar in a small bowl with electric mixer until light and fluffy. Transfer mixture to large bowl, and stir in sifted flours using a wooden spoon. Chill in the refrigerator for 30 minutes.
With floured hands, roll rounded teaspoonfuls of mixture into balls. Place balls about 2.5cm apart on trays to allow room for spreading, and then flatten slightly with the back of a lightly floured fork. I used star nozzle to pipe rosette shaped cookies too.
Bake cookies about 15 minutes or until just cooked through and light golden. Stand 5 minutes in tray before lifting onto wire racks to cool. Dust with extra sifted icing sugar before serving, if you like.