Cremsnit - Vanilla Custard Slice

For the pastry:

1. To make the dough, mix the flour with the egg, water and salt to combine. Knead for 10 minutes, then cover and refrigerate for 1 hour. Gently beat the butter with a sprinkling of flour to form a spreadable blend. Set aside in a warm place but don't allow to melt.
2. Flour the work surface and roll the dough to a 35 x 40cm (14 x 15¾in) rectangle, with the long side parallel to you. Spread 100g (3½oz) of the butter mixture onto two-thirds of the dough rectangle from left to right. Fold the right side (without butter) two thirds across the rectangle, then fold the left side over to overlap it. Bring the bottom half to the middle, and the top half to completely overlap the bottom half. It needs to look like a closed book. Now turn its spine to your left. You may need to keep flouring the work surface and the dough to prevent everything from sticking.
3. Roll again to a smaller rectangle than before and repeat the process above, using 75g (3oz) of the butter mixture. Roll again and repeat the steps using the remaining butter (you need to roll the dough out three times in total). Wrap in cling film and refrigerate for at least 1 hour or ideally overnight. The dough can also be chilled in the fridge for 30 minutes before the last folding.

For the vanilla custard slice:

1. Preheat the oven to 200°C/400°F/gas mark 6. If using homemade pastry, divide the dough in 2. Roll both halves to 30 x 35cm (12 x 14in) rectangles around 5mm (¼in) thick and place on lined baking sheets. Bake for 20-25 minutes until golden and crisp. While still warm, trim one pastry rectangle to the size of the baking dish you will use to assemble the cake (mine was 23 x 28cm / 9 x 11in). Reserve the trimmings for the topping.
2. To make the vanilla cream, mix the egg yolks with the sugar, then add the flour and cornflour. Heat the milk with the vanilla in a pan over a medium heat, then gradually add to the egg mixture, stirring continuously. Return the mixture to the pan, bring to a simmer and whisk until thickened. Remove from the heat and leave to cool for 15 minutes, then add the butter, combining well. Set aside to cool completely.
3. To make the whipped cream, whisk the double cream with the icing sugar until it forms soft peaks, then stir in the vanilla and orange liquor, if using. Set aside.
4. To assemble the cake, line the baking dish with cling film, allowing it to overhang on each side. Place the trimmed pastry layer into the dish, spread the vanilla cream on top, then add the whipped cream. Cover with the extra cling film and set in the fridge overnight. When you are ready to serve, crumble over the remaining pastry rectangle and leftover trimmings. Cut into rectangular slices and dust with icing sugar.