Crème Brûlée Tart

Grease a 9-inch round tart pan with removable bottom. Process flour, custard powder and butter until crumbly. Add 1 egg yolk and enough water (about 1 tbsp) to make ingredients just cling together. Press dough into a ball. Knead on floured surface until smooth. Wrap in plastic wrap. Refrigerate for 30 mins.
Roll pastry between 2 sheets parchment paper until large enough to line tart pan. Press pastry into pan; trim edge. Refrigerate for 30 mins.
Preheat the oven to 400u0b0F. Line pastry shell with parchment paper. Fill with dried beans or rice and place on a baking pan. Bake for 10 mins. Remove paper and beans. Bake a further 10 mins or until pastry is lightly browned. Cool.
Reduce oven temperature to 300u0b0F. Meanwhile, for the filling, whisk remaining 4 egg yolks and sugar in large bowl until thick and creamy.
Split vanilla bean lengthwise and scrape seeds into medium saucepan. Add cream and milk and bring to a boil. Remove from heat. Whisk hot milk mixture into egg yolk mixture. Strain into a clean bowl. Cool.
Pour filling into tart crust. Bake tart for about 1 hour or until custard is set. Remove from oven. Cool on a wire rack.
For the topping, sift sugars together twice through a fine sieve. Sift topping evenly over filling. Refrigerate for 1 hour.
Preheat the broiler. Cover pastry edge of tart with foil. Place tart under hot broiler for 2 mins or until sugar is melted and golden brown. (If sugar does not melt in 2 mins, lightly brush topping with water and broil again.)