Lemon meringue pie

melted butter, for greasing
1 1/2 cups plain flour
1/2 tsp baking powder
125g chilled butter, cubed
2 tbsp chilled water
extra flour for kneading

Filling:
1/2 cup plain flour
1/2 cup cornflour
1/2 cup caster sugar
juice 4 large lemons (or limes)
1/2 cup water
60g butter
3 eggs, separated
extra 3/4 cup caster sugar

1. Preheat oven to 200 C. Brush four 10cm bluted loose bottomed flan tins with butter. Put flour, baking powder and butter in a food processor and process until mixture resembles breadrumbs. Add water; process until mixture comes together. Turn out onto a lightly floured surface and knead until smooth. Divide into 4 equal portions and roll out between 2 sheets of baking paper. Line each tin with pastry. Refrigerate for 20 mins.
2. Put a square of baking paper over pastry, fill with baking beads and bake for 10 mins. Remove beads and paper and return to oven and cook for a further 10 mins or until golden. Cool.
3. To make filling, combine flour, cornflour and sugar in a heavy-based pan. Gradually add in juice and water, stirring constantly, until combined. Stir over a low heat until mixture boils and thickens. Remove from heat and stir in butter and yolks. Return to heat and stir until butter is melted. Cover surface with plastic wrap and cool. Spoon cold mixture into cold shells.
4. Beat eggwhites util stiff peaks form. Add extra sugar, gradually, beating for 5 mins or until well combied, thick and glossy. Spoon meringue into a piping bag with a star nozzle and pipe stars over surface of pies. Bake for 5 mins or until lightly browned. Serve immediately.