In a medium mixing bowl, combine egg yolks and granulated sugar. Whip on high speed for about 2 minutes until pale and fluffy.

In a saucepan, gently warm heavy cream with a pinch of sea salt over low heat, stirring occasionally until steaming.

Gradually pour the warm cream into the egg yolk mixture, whisking continuously. Return to the saucepan and cook over low heat, whisking for 3-5 minutes until thickened.

Remove from heat and add chopped bittersweet chocolate and vanilla extract. Stir until melted and smooth.

Transfer to a mixing bowl and cool at room temperature for about 30-40 minutes, stirring occasionally.

In a chilled bowl, whip the remaining heavy cream until stiff peaks form, about 3-5 minutes.

Gently fold whipped cream into the cooled chocolate mixture until fully combined.

Spoon or pipe the mousse into individual dessert cups and refrigerate for at least 2 hours.

Top with whipped cream and chocolate shavings before serving.