- Heat oven to 170°C. Lightly grease a 22cm spring form cake tin. Beat butter and caster sugar together until pale and creamy. Beat in vanilla seeds and extract.
- Sift dry ingredients together and add to mixture, beating gently just enough to incorporate and form a smooth dough.
- Press the dough into the prepared cake tin. Prick all over with a fork. Bake for 25 to 30 minutes or until golden and set. Remove from the oven and immediately dust with caster sugar. Cool in the tin for 15 minutes, then remove and cut into wedges before cooling completely.
Tip: Shortbread will last up to one week if it's stored in an airtight container.