Gather 8 ounces of dark chocolate, 3 large eggs, 2 tablespoons of sugar, 1 teaspoon of vanilla extract, and 1 cup of heavy cream.
Melt the dark chocolate in a heatproof bowl over simmering water or in the microwave, then let it cool slightly.
Separate egg yolks from whites, placing yolks in one bowl and egg whites in another.
Whisk egg yolks with sugar until pale and slightly thickened, then stir in the melted chocolate and vanilla extract.
In a separate clean, dry bowl, whip egg whites until stiff peaks form.
Gently fold the whipped egg whites into the chocolate mixture until well combined.
In another bowl, whip the heavy cream until it forms soft peaks.
Fold the whipped cream into the chocolate mixture until smooth and well incorporated.
Spoon the mousse into serving glasses or bowls and refrigerate for at least 2 hours to set.
Garnish with chocolate shavings or berries before serving. Enjoy the luscious and airy Dark Chocolate Mousse!