Basic Recipe adapted from here....
1/2 cup cornstarch/cornflour
1/2 cup icing sugar
1 cup rice flour
3/4 cup (170g) butter, chilled and diced
1. Preheat Oven to 150C, 300F
2. Sift cornflour, rice flour and icing sugar together into a large bowl
3. Add chilled, diced butter and rub in to dry mix using fingertips
4. Bring dough together and refrigerate for 1 hour. NB - As I was making 4 different kinds of shortbread I split my dough into 4. To one I added grated orange zest, the second cinnamon, and the third and fourth I left plain. Before chilling I rolled each quarter into a 2" sausage so I could just slice them into cookies after an hour.
5. Remove from fridge and slice into 24 cookies, place on greased baking trays, pricking or scoring the tops with a fork. NB - To the ones I had left plain I added demerara sugar to the top of half and vanilla sugar to the remaining 6. Bake for 20-25 minutes, be careful not to overbake as they will crumble rather than crunch.