01 - Melt dark chocolate in a heatproof bowl set over simmering water, stirring until smooth. Remove from heat and cool slightly.
02 - In a clean bowl, whisk egg yolks with vanilla extract and half the sugar (2 tablespoons) until pale and creamy.
03 - Gently fold melted chocolate into the egg yolk mixture until fully incorporated.
04 - In another bowl, beat egg whites with the remaining sugar (2 tablespoons) until stiff peaks form.
05 - Whip cold heavy cream until soft peaks develop.
06 - Fold whipped cream into the chocolate mixture until homogeneous.
07 - Carefully fold beaten egg whites into the mixture in three additions until smooth and airy.
08 - Divide mousse evenly among six serving cups or glasses.
09 - Refrigerate for at least 2 hours until set.
10 - Top each mousse with fresh raspberries, optional chocolate shavings, and mint leaves before serving.