• 250g butter, softened
• 1 cup pure icing sugar, sifted
• 2 tsp vanilla extract
• 21⁄4 cups plain flour
• 1⁄4 cup rice flour
• Extra flour, for kneading
• 1 eggwhite, whisked
• 1 Tbsp white sugar
Preheat oven to 160°C. Line 2 oven trays with baking paper and draw an 18cm circle in centre of each sheet.
Put butter, sugar and vanilla in the bowl of an electric mixer and beat until light and creamy. Sift plain flour over butter mixture and stir until a soft dough forms. Add rice flour and stir until well combined. Turn out dough onto a lightly floured surface and knead until smooth.
Halve dough. Gently press each half into a flat disc and transfer to centre of circles on baking paper. Gently press out with your fingers to form 1.5cm-thick 18cm rounds.
Using your fingertips, pinch edge of each round to form a frill. Using a large knife, score 12 triangles in each round, without cutting through dough. Refrigerate for 10 minutes or until firm.
Brush rounds with eggwhite and sprinkle with sugar. Bake for 5 minutes. Swap trays and bake for a further 15 minutes or until firm to touch. Cool completely on trays. Cut into pieces and serve.