Step 1

Preheat oven to 170C/150C fan-forced. Grease an 18cm x 28cm slice pan. Line base and sides with baking paper, extending paper 2cm above edges of pan.

Step 2

Using an electric mixer, beat butter, lemon rind and vanilla until light and fluffy. Gradually beat in icing sugar until well combined. Add egg. Beat until combined. Gradually beat in flour, in 2 batches. Spoon mixture over base of prepared pan. Using damp hands, press mixture to cover base evenly.

Step 3

Bake for 20 to 25 minutes or until edges just start to turn golden and top is just firm. Cool completely in pan.

Step 4

Make Fluffy Lemon Icing. Using electric mixer, beat butter and lemon rind until light and fluffy. Gradually beat in icing sugar until smooth and combined. Beat in lemon juice. Spread icing over top of slice. Decorate with lemon zest. Cut into pieces. Serve.