Step 1

Grease an 18cm loose-bottomed tart pan and dust with a little flour.

Step 2

Place butter in the bowl of an electric mixer and beat until light and fluffy. Add remaining ingredients, then beat on low speed for around 5 minutes until combined - the mixture should resemble fine breadcrumbs. Press into the prepared pan, flattening by pressing the top with a piece of baking paper. Use a sharp knife to mark out 8 wedges on the top of the shortbread (not cutting all the way through) and prick all over with a fork. Cover and chill for 30 minutes.

Step 3

Preheat oven to 170°C. Bake shortbread for 30 minutes or until light golden, then remove from oven and sprinkle with extra sugar. Leave in the pan to cool completely before cutting into wedges following the indents. Serve with tea.