Seeds from 1 vanilla pod / 1/2 teaspoon vanilla bean paste
25g plain flour
For the passionfruit glaze:
125g cups icing sugar
15g unsalted butter, melted
2 small passionfruit, pulp only (about 40 grams)
Make the pastry layers: Preheat oven to 180C/160C fan. Place each pastry sheet on a large oven tray lined with baking paper. Dust 1 tablespoon of icing sugar until covered with a thin layer of icing sugar, then place another sheet of baking paper on top and weigh down with another tray. Bake for 20 minutes, then remove the top baking tray and paper and cook for another 10 minutes until crisp and golden. Cool on a rack and repeat with the second sheet of pastry.
Make the creme patissiere: Put the milk into a saucepan and bring it to a simmer, then take it off the heat and let it cool for a few minutes. Put the eggs and sugar into a large mixing bowl and whisk them together, then add in the flours and vanilla and whisk them through. Tip the warm milk into the egg mix, mix it all together then return the whole mixture to the saucepan over a low heat, and use the whisk to stir constantly while you bring it to the boil. Once the custard has reached a boil and thickened substantially, remove it from the heat and let it cool for 5 minutes while you prepare the base.
Cut two long strips of greaseproof paper, each the width of your 20 centimetre square cake tin. Lay one piece across the tin, so that it lines the bottom and 2 sides, and hangs over each side. Repeat with the second piece of paper, in the other direction so all four sides are lined. Trim the pastry sheets to fit snugly in the pan and place 1 sheet in the base. Pour in the warm custard mixture, use a small palette knife or the back of a spoon to smooth it over, then top with the remaining pastry sheet and press it down firmly but gently. Chill for 4 hours, or until set firm.
Make the passionfruit icing: Sieve the icing sugar into a bowl then add the melted butter and passionfruit pulp and stir until smooth. Spread the icing over the chilled slice while it’s still in the tin, the put it back into the fridge for half an hour. Once the icing has set, use the paper strips to carefully lift the whole slice from the tin. Use a pastry knife to slice into 8 rectangles, then serve.