Cooking oil spray, to grease
250 g shortbread biscuits
2 tbsp cocoa powder
100 g unsalted butter, melted
400 g dark chocolate (70% cocoa), finely chopped
275 ml pure cream
1 cup hazelnuts, toasted, roughly chopped
100 g milk chocolate (40% cocoa), finely chopped
- Grease a 30 x 8cm rectangular loose-bottomed fluted tart tin with cooking oil spray. Line base with baking paper.
- Put biscuits in a large zip-lock bag and crush with a rolling pin until fine crumbs form. Transfer to a large bowl and stir in cocoa and butter. Press into bottom of prepared tin and chill until firm.
Meanwhile, put dark chocolate in a large heatproof bowl over a saucepan of simmering water and stir until half-melted. Remove from heat and set aside.
- Pour 200ml of the cream into a small saucepan and bring to the boil over medium heat. Add to dark chocolate whisking until smooth. Sit bowl in a large bowl of iced water, ensuring no water gets into the chocolate mixture, and beat until thick and aerated. Fold in ¾ cup of the hazelnuts, then spoon onto biscuit base and smooth surface. Chill until firm.
- Heat remaining cream in a small saucepan. Once boiling, remove from heat and whisk in milk chocolate until smooth. Transfer to a bowl and chill for 10 minutes or until slightly thickened and spreadable. Remove slice from tin. Spread chocolate mixture over slice and scatter with remaining hazelnuts. Chill for 5 minutes until set, then cut into slices.