Melt the chocolate. You can do it in a microwave-safe bowl in the microwave, using bursts of 30 seconds, then stir, repeat until melted. Or use the double boiler method on the stovetop.
Now add the heavy whipping cream to a large bowl and beat until you have soft peaks. When you pull up the beaters the peak that is formed will keep its shape but will fold over.
In a separate bowl, crack the eggs and transfer the yolk back and forth from each half of the shell, this will allow just the egg white to drop into the bowl.
Beat the egg whites until frothy, then set the mixer to medium, and as you are beating add a little bit of the sugar at a time. Continue doing this until all the sugar is incorporated and you are left with soft peaks.
Now pour the melted chocolate into the bowl with the egg whites. Then fold it in with the spatula. DO NOT stir.
Add in the whipped cream about 1/4th of it at a time, and fold it in until incorporated, then add in the next 4th, etc. The mousse is done.
Add the chocolate mousse to your chosen containers and chill in the fridge for about 2 hours. Then right before serving, top it off with whipped cream, chocolate shavings, sprinkles, nuts, coconut flakes, etc. Enjoy!Refrigerated leftovers, covered, for up to 5 days.