Pastry: 2 and a half cups of flour, one-third of a cup icing sugar, quarter cup cornflour, half teaspoon salt, 250g butter (at room temperature), zest of one lemon.
Filling: 4 eggs lightly beaten, one a quarter cup sugar, 3 tablespoons flour (sifted), zest of two lemons, two-thirds of a cup of lemon juice, one-third of a cup of milk, quarter teaspoon salt.
Preheat the oven to 170 degrees C. Grease and line a 30 x 20 cm baking tin. In the food processor pulse all dry ingredients until well combined. Add butter. Pulse till resembles a coarse meal. Scatter over tin and press firmly into an even layer. Leave edges raised slightly. Place in fridge for 20 minutes. Then bake for 20 minutes. Remover from oven and allow to cool slightly.
Turn the oven down to 150 degrees C. In a bowl whisk together eggs, sugar and flour. Stir in juice, zest, milk and salt. Mix till combined. Pour filling over warm crust. Bake for a further 15 to 20 minutes. Cool completely before lifting out of the tin to cut.