2 sheets of ready-rolled frozen puff pastry, thawed rolled to a 2mm (1/16in) thick and cut into two 23cm (9in) squares
Cooking oil spray
For the crème patissiere:
375 ml (13floz) thin (pouring) cream
125 ml (4floz) full-cream milk
7 egg yolks
75g (2¾oz) caster sugar
1½ tsp pure vanilla extract
2 tbsp plain flour
1½ tbsp cornflour
For the passionfruit icing:
185g (6½oz) icing sugar
1 tbsp unsalted butter, melted and cooled
2 tsp passionfruit pulp
2 tsp boiling water
- Make the crème pâtissière by gently heating the cream and milk in a saucepan over medium heat until it comes almost to the boil. Remove from the heat. Meanwhile, in a bowl, whisk together the egg yolks, sugar, vanilla, flour and cornflour until smooth. Constantly whisking, gradually pour the warm milk mixture into the egg mixture. Pour into a clean, heavy-based saucepan and stir over low heat for 15 mins, or until the custard is very thick and smooth. Remove from the heat, pour into a bowl and cover with a sheet of baking paper, pressing it down directly onto the surface of the custard to prevent a skin forming.
- Preheat the oven to 220°C/425°F/Gas Mark 7. Place each pastry sheet on a large, lightly greased baking tray, prick all over with a fork, then sit another clean baking tray on top to weigh the pastry down slightly, making it rise evenly. Bake for 20–25 mins, or until deep golden all over. Allow to cool completely on the baking trays, placed on wire racks, then trim the edges so that each pastry sheet will fit into a 22–23cm (8½–9 in) square cake tin.
- Lightly spray the base of your cake tin with cooking oil spray. Line the base with a sheet of baking paper long enough to come up the sides and well overhang them — this is important, as it will help you lift the vanilla slice out of the tin once the custard layer has set.
- Gently fit a pastry sheet into the base of the tin, then dollop the warm crème pâtissière over the top, smoothing the surface so it is level. Top with the second sheet of pastry, with the flattest side facing up. Press down slightly to help it adhere to the custard, then refrigerate for several hours, or until the custard is completely cold and more firm.
- When you are ready to ice the top, make the passionfruit icing by mixing all the ingredients together until smooth. The icing should have a slightly flowing, spreadable consistency. Pour the icing over the top of the pastry and use a crank-handled or offset spatula to spread it evenly to the edges. Return to the fridge and allow to set for about 1 hour or so.
- When ready to serve, lift the custard slice out of the tin and onto your work surface, using your baking-paper handles. Use a long, sharp serrated knife to cut the slice into 10 even, rectangular pieces.
- Serve with a dessert fork, as the custard is a little softer than one that has been firm set with gelatine … and so it may squeeze out the sides and down your front when you bite down!
- If you’re not serving the slice straight away, store it in a single layer in an airtight container. It will keep in the fridge for up to 4 days.
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Also known as vanilla slice, Napoleon slice, and the far less appetising ‘snot block' there have been several incarnations of the custard slice over the decades
Time: 30 minutes