1. Preheat oven to 160oC/325oF. Line baking sheet or flat oven tray with parchment paper.
2. 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. If the mixture is too soft and sticky, chill in the refrigerator for 30 minutes.
3. 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.
4. 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.
5. To make the filling (if using), beat butter, sifted icing sugar and rind in small bowl with electric mixer until pale and fluffy; beat in juice. Sandwich cookies with butter cream.
6. Unfilled biscuits will keep in an airtight container, between sheets of waxed or parchment paper, for up to a week. Use metal tins to keep the cookies firmer. Filled biscuit will keep for a few days in an airtight container in the fridge.
7. This basic recipe is highly adaptable. Try using custard powder instead of corn flour for a delicious twist. Other variations are to use 1/2 tsp cardamom powder instead of vanilla extract, if you like. For variations in shape, use a star nozzle to pipe rosette shaped cookies. Alternatively, you can emboss the cookies with lovely motifs using a cookie die, medallion, coin, or just leave them plain. For a lovely variation in filling, if using, mix in one strained passionfruit pulp instead of rind and juice of one lemon.

Whatever your choice, these taste phenomenal!