2 x 25cm square sheets pre-rolled butter puff pastry
½ cup caster sugar
1 tablespoon butter
1 teaspoon vanilla extract
¼ teaspoon sea salt
6 large egg yolks, size 7
½ cup cornflour
100 grams chopped chocolate (I used Whittakers Sea Salt and Caramel Brittle)
2 tablespoons cream
1 tablespoon water
1 tablespoon melted butter
1½ cups icing sugar, sifted
extra chocolate for grating
Line a 20cm square cake tin with a piece of baking paper making sure it has an overhang on opposite sides. These handles help lift the finished slice from the tin.
Preheat the oven to 170°C fan bake.
Prick each sheet of pastry with a fork. Place on a flat, lined baking tray. Place another sheet of baking paper over the top and cover with a 2nd baking tray. Bake for about 17 minutes until a good golden colour. Transfer to a cooling rack and repeat with the second sheet of pastry.
Carefully trim the pastry sheets to a 20cm square, reserving the scraps for decoration. Place one sheet in the base of the tin.
Custard: Put the milk, cream, sugar, butter, vanilla and salt in a medium saucepan and heat until just below boiling point.
Whisk the egg yolks and cornflour together in a heatproof bowl until smooth. Gradually whisk in the hot milk mixture then tip back into the saucepan.
Place over a low heat and cook for 5 minutes, whisking constantly, until it just comes to the boil and is very thick and the cornflour is cooked out. Take off the heat and stir in the chocolate until smooth.
Pour the hot custard over the pastry base and top with the second sheet and gently press it on to the custard. Cool then cover and refrigerate overnight or until the custard is set – about 8 hours.
Combine the cream, water and butter together, then stir into the icing sugar to make a thick but spreadable icing. Add more water or icing sugar if necessary to get the right consistency.
To finish: Spread the icing over the top layer of pastry. Crush some of the pastry trimmings over the top of the wet icing then grate over a little dark chocolate. Chill to set the icing, then use the baking paper to help lift the slice from the tin. Use a sharp serrated knife to cut into squares. Store the slice in a covered container in the fridge. Makes 12 squares