Step 1

Preheat oven to 180C/160C fan forced. Grease a 3cm-deep, 16 x 25cm slice pan and line with baking paper, allowing the paper to overhang above the long sides.

Step 2

Place the plain flour, cornflour, icing sugar and vanilla in a food processor. Process until the mixture is well combined. Add the butter and process until the mixture just starts to come together. Stir in the pistachio and lemon rind. Press the mixture firmly over the base of the prepared pan. Bake for 20 minutes or until light golden then set aside to cool completely.

Step 3

Place the lemon butter in a small bowl. Whisk until smooth then spread over the shortbread layer.

Step 4

Use electric beaters to beat the egg whites in a small clean, dry bowl until soft peaks form. Gradually add the caster sugar, beating well after each addition, until the sugar dissolves and mixture is thick and glossy. Spoon the meringue into a piping bag fitted with a fluted nozzle and pipe on top of the lemon butter layer (see tip).

Step 5

Bake for 3-5 minutes or until lightly browned. Set aside in the pan for 15 minutes to cool before slicing.