Haigh’s Chocolate Vanilla Slice

• 375g pack all butter puff pastry, thawed (eg. Careme) 

Chocolate & vanilla crème pâtissière 

• 100g Haigh's dark chocolate pastilles, roughly chopped 
• 375ml (1½ cups cups) milk
• 375ml (1½ cups) pure cream
• 40g unsalted butter, diced
• 2 teaspoons vanilla bean paste
• 8 egg yolks
• 150g (2/3 cup) caster sugar 
• 2 tablespoons cocoa powder
• 2/3 cup (100g) cornflour, sifted

Vanilla & chocolate icing

• 50g Haigh’s dark chocolate pastilles, melted 
• 1 ½ cups icing sugar, sifted
• 1 teaspoon vanilla bean paste
• 2 tablespoons water

1. Preheat oven to 200C (180C fan-forced). Line 2 x baking trays and a 22cm square cake tin with baking paper, with enough paper to overhang the edge of each side of the cake tin (to help lift the slice out).
2. Cut pastry into a rectangle 30cm wide x 45cm long and cut into two equal halves. Lay on prepared baking trays and prick all over with a fork. Place another sheet of baking paper on top followed by another baking tray and bake for 15 minutes in preheated oven or until golden. Place pastry sheet on wire rack to cool before trimming edges to 22cm. Repeat process with remaining pastry sheet.
3. Meanwhile to make the crème pâtissière combine the milk, cream, butter and vanilla together in a medium saucepan over medium heat. Bring to the boil, remove from heat and allow to infuse for five minutes.
4. In a medium bowl, whisk together the egg yolks, sugar, cocoa and cornflour until well combined. Gradually whisk in the hot milk. Pour egg mixture into a clean saucepan, over medium heat, whisking continuously for 5 minutes or until custard becomes very thick, smooth and glossy. Remove from heat and allow to cool for 5 minutes before adding the chocolate, stirring until melted and combined. Set aside until required.
5. Place a prepared pastry square in prepared cake tin and spoon over the custard, spreading evenly to cover the pastry. Place the second pastry sheet on top, pressing down gently, to sandwich the custard. Place tin in refrigerator and allow to chill for 4 hours, preferably overnight.
6. For the icing, combine icing sugar, vanilla and water together in a small mixing bowl, stirring until smooth. Carefully spread the white icing over the top of the slice. Using a small piping bag, drizzle lines of melted chocolate over the top and then carefully run a knife or skewer up and down repeating process, to create a feather like design. Refrigerate for 30 minutes, to allow icing and chocolate to set.
7. To serve, use a hot dry serrated knife to carefully cut through the pastry and custard layers. This is a delicate process, so best not to rush it.