1	Preheat oven to 200C. Halve pastry and roll each piece to 19cm square, place on baking paper-lined oven trays and refrigerate for 30 minutes. Trim each to 18cm square, prick all over with a fork, and bake for 15 minutes or until puffed and golden. Cool on a wire rack, then halve each piece horizontally, using a serrated knife, to give four squares.
2	For custard, combine sugar and cornflour in a saucepan over medium heat, add milk a little at a time, whisking until smooth. Add juice and vanilla seeds. Bring just to the boil, whisking until smooth and thick. Remove from heat, whisk in yolks and butter and set aside.
3	Line an 18cm-square cake pan with baking paper, place a piece of pastry in base and pour over a third of the custard, level with a palette knife and top with another piece of pastry. Repeat with remaining custard and pastry. Stand for 2 hours or until set.
4	For icing, combine ingredients in a bowl and mix. Spread over slice and serve.

Note To make passionfruit juice, blend passionfruit pulp in a food processor to crack seeds, then strain through a fine sieve. Twelve passionfruit yield about 1 cup of juice.