Step 1

Preheat oven to 180°C/160°C fan-forced. Grease a 3cm-deep, 16cm x 26cm slice pan. Line with baking paper, allowing a 2cm overhang on all sides.

Step 2

Place butter in a large microwave-safe bowl. Microwave on MEDIUM (50%) for 1 minute or until melted. Set aside to cool. Stir in vanilla and sugar. Sift flours over butter mixture. Using a wooden spoon, stir until a soft dough forms. Transfer to prepared pan. Press into pan. Bake for 15 to 20 minutes or until golden. Remove from oven. Set aside to cool.

Step 3

Make topping Whisk eggs, lemon rind, flour and sugar together until smooth. Add lemon juice. Whisk to combine. Pour over base. Bake for 15 minutes or until just set. Cool completely in pan. Dust with icing sugar. Cut into pieces. Serve.