Preheat oven to 220°C (200°C fan-forced). Line a baking tray with baking paper.
Cut pastry into three equal rectangles 27cm x 9cm and lay on prepared baking tray. Place another sheet of baking paper on top followed by another baking tray on top and bake for 10 minutes in preheated oven then reduce oven to 200°C (180°C fan forced) and bake for a further 30 minutes or until pastry is golden.
Meanwhile to make the crème pâtissière combine the milk, cream, vanilla bean paste and zest together in a medium saucepan over medium heat. Bring to the boil, remove from heat and allow to infuse for five minutes.
Whisk together the egg yolks, sugar and flours in a medium bowl. Gradually whisk in the hot milk. Pour egg mixture into a clean saucepan, over medium heat, stirring continuously until the mixture boils and thickens.
Strain through a fine sieve into a medium bowl, stir in the butter to loosen custard, cover the surface with plastic wrap and chill in the refrigerator.
For the icing, combine icing sugar and water together in a small mixing bowl, stirring until smooth. Place 1 tablespoon of the mixture in another small mixing bowl and add cinnamon, stirring to combine.
To serve, place one sheet of the baked pastry on a serving plate. Spread or pipe half the pastry cream over the pastry. Place a second sheet of pastry on top and pipe remaining pastry cream. Place the final sheet of pastry on top and carefully spread over the white icing.
Using a small piping bag, drizzle lines of the cinnamon icing over the top and then carefully run a knife up, down and back up, to create a feather like design.