- Preheat oven to 180C. Line 2 baking trays with baking paper. Place butter, sugar and vanilla into a food processor. Process for 2 minutes. Add flour and custard powder. Pulse until just combined. Roll heaped teaspoonfuls of mixture into small balls. Place onto prepared baking trays. Press with a floured fork to flatten slightly. Bake for 12 minutes. Allow to stand on trays for 2 minutes before transferring to a wire rack to cooling rack. Let it cool down. Then store.