Start by placing the finely chopped semi-sweet chocolate in a mixing bowl. Carefully pour the boiling water over the chocolate. Allow it to sit for a minute to soften, then stir until completely smooth and melted.
Once the chocolate is smooth, add the pasteurized egg to the mixture. Blend on low speed just until the egg is fully incorporated.
In a separate mixing bowl, whip the heavy cream until soft peaks form. Add the vanilla extract during the whipping process.
Using a rubber spatula, gently fold the whipped cream into the chocolate mixture.
Once everything is combined, spoon the mousse into your serving dishes. Cover with plastic wrap and refrigerate for at least 2 hours, or until set.
When ready to serve, remove from the fridge, garnish with additional whipped cream or chocolate shavings if desired, and enjoy!
