Preheat the oven to 200℃ (180℃ fan)/400°F/gas mark 6. Lightly grease a shallow
Unroll the pastry and remove the lining sheet, then reroll to form a log of pastry. Cut into 1.5cm (½in) thick slices.
Lay each piece on a lightly floured surface and roll out each round until they are 9cm (3½in) in diameter. Arrange in the prepared tin so that they overlap slightly and cover the base and sides of the tin. Press the pieces together stretching the pastry slightly if required to make sure there are no gaps between the pieces.
Line the pastry case with baking parchment and fill with baking beans. Bake for 20 minutes then remove the parchment and beans. Lightly beat the egg white and brush the surface of the pastry with egg white. Return to the oven for 5 to 10 minutes until the pastry is just beginning to colour and feels dry.
Meanwhile make the custard. Place the custard powder and sugar in a bowl with the vanilla paste and egg yolks. Add a little milk and whisk to form a smooth paste.
Heat the milk with the cream in a saucepan until almost boiling. Gradually whisk the hot milk into the egg yolk mixture, then return to the pan. Heat gently stirring constantly until the custard thickens slightly.
When the pastry case comes out of the oven, reduce the oven temperature to 180℃ (160℃ fan)/350°F/gas mark 4. Pour the custard into the pastry case and bake for 40 minutes.
Allow to cool in the tin for 5 minutes then transfer to a wire rack to cool completely . Serve cold.