Preheat the oven to 180^oC. Place butter, sugar and cinnamon in a food processor and process until smooth. Add the flour, egg, extra egg yolk and water. Process until the dough is smooth. Knead the dough lightly and wrap in a plastic wrap. Refrigerate for 30 minutes.

Roll out the dough on a clean, floured work surface until about 5mm thick. Cut into star shapes using a cookie cutter. Place on baking trays and bake for approximately 10-12 minutes until golden. Cool on wire racks and store in an airtight container.