01 - Melt the dark chocolate in a heatproof bowl set over simmering water, stirring until smooth. Remove from heat and allow to cool slightly.
02 - Whisk the egg yolks with vanilla extract and half of the sugar until pale and creamy.
03 - Gently fold the melted chocolate into the egg yolk mixture until fully incorporated.
04 - In a clean bowl, beat the egg whites with the remaining sugar until stiff peaks form.
05 - Whip the cold heavy cream until soft peaks develop.
06 - Fold the whipped cream into the chocolate mixture until evenly combined.
07 - Carefully fold in the beaten egg whites in thirds, preserving the airy texture.
08 - Divide the mousse evenly among 6 serving cups or glasses.
09 - Refrigerate for at least 2 hours until the mousse is set.
10 - Just before serving, garnish each mousse cup with fresh raspberries, chocolate shavings, and mint leaves if desired.