Method

• 1.
  For the chocolate mousse, place chocolate and butter in a heatproof bowl over a saucepan of simmering water (don’t let the bowl touch the water), stirring occasionally, until melted.
• 2.
  Whisk egg yolks and sugar in a large bowl until pale, creamy and doubled in size. Whisk chocolate mixture into yolk mixture until combined.
• 3.
  Whisk egg whites and a pinch of fine salt in the bowl of a stand mixer fitted with the whisk attachment and whisk on medium-high speed until soft peaks form. Add one-quarter of the egg white mixture to the chocolate mixture and whisk until combined. In three batches, gently fold in remaining egg white mixture. Chill for 3-4 hours to firm.
• 4.
  To make the cake, preheat oven to 180°C/160°C fan-forced. Line a baking tray with baking paper. Trace a 20cm round onto paper, then flip paper over. Sift hazelnut meal, icing sugar, flour and a pinch of fine salt into a large bowl. In the bowl of a stand mixer fitted with the whisk attachment, whisk egg whites on medium-high speed until frothy. Add caster sugar and whisk until firm peaks. Sprinkle over one-third of the hazelnut mixture and gently fold in until just combined. Repeat in two more batches (do not overmix or the egg whites will collapse). Spoon onto prepared tray and form a round, using the circle as a guide. Dust with extra icing sugar, then sprinkle with chopped hazelnuts. Bake for 30 minutes or until golden. Cool completely on tray.
• 5.
  Transfer hazelnut cake to a serving plate, top with mousse and raspberries, then sprinkle with pistachio, freeze-dried raspberries (if using) and extra shaved chocolate to serve.