1. For pastry, beat butter and icing sugar in an electric mixer, fitted with a paddle attachment, until creamy. Stir through flour, then yolks, and wrap dough and refrigerate to rest.

2. For lemon filling, slowly blend eggs, sugar and juice in a blender just until combined, then while blending, add lemon juice until just combined. Refrigerate overnight to settle the froth, then remove the foam from the top of the mixture, and gently stir to combine.

3. Preheat oven to 190°C. Blind bake pastry shell using baking paper and pastry weights, such as dried legumes to fill, until edges are golden (30 minutes). Remove paper, reduce oven to 150°C and bake pastry shell until base is dried (15 minutes). Remove pastry from oven, then brush any holes or cracks liberally with the reserved egg white to seal them, then return tart to the oven. Carefully pour the filling into the tart case, and then bake until set with a slight wobbly just in the centre (45 minutes). Set aside to cool completely on a wire rack.

4. For Italian meringue, combine sugar and 60ml water in a small saucepan over medium heat, stir until sugar dissolves and brush down sides of pan with a wet pastry brush to remove any sugar particles. Increase heat to high and cook until syrup reaches 121°C on a sugar thermometer (6-9 minutes). Meanwhile, when syrup reaches 110°C, start whisking egg whites and a pinch salt in an electric mixer until soft peaks form. Gradually pour hot syrup over egg whites in a thin stream, whisking continuously until cooled, thick and glossy (10-12 minutes).

5. To serve tart, pipe meringue over tart with a piping bag fitted with a St Honoré nozzle, piping in a wave like motion in alternating lines across the tart. Caramelise the top with a blow torch if desired, then serve. Tart must be cooled to serve, and is best eaten the day of making, but will keep refrigerated for up to 2 days in an airtight container.