For the mousse, whisk the egg whites until stiff peaks form when the whisk is removed, then fold in the sugar.
Whip the cream until soft peaks form when the whisk is removed, then fold into with the egg whites and sugar mixture.
Add the melted chocolate and fold through to create a marbled effect.
For the hazelnut praline, heat the sugar and nuts in a pan over a medium heat. Stir occasionally until the sugar has melted and caramelised and the hazelnuts are golden-brown. Pour the praline mixture onto a silicone mat and leave to cool and set. Break up the praline into shards.
For the coulis, place all of the coulis ingredients into a food processor and blend until smooth. Pass the coulis through a sieve to remove the pips.
To serve, spoon the mousse into a tall serving glass. Scatter the hazelnut praline sprinkle over the top and drizzle the raspberry coulis over to finish.