In a bowl of an electric mixer, whisk your heavy cream until stiff peaks form. Transfer to a different bowl. Cover with plastic wrap and keep in the fridge.
In a large heatproof bowl, whisk together egg yolks, orange juice, salt, and 1/4 cup of your sugar. Set the bowl over a pot of simmering water. Make sure the water is not touching the bowl. Whisk constantly until the sugar has dissolved, the mixture is lighter in color, and about doubled in size (about 5 minutes). Remove the bowl from heat. Whisk in your chocolate until melted and smooth. Allow your mix to cool to room temperature, whisking occasionally.
Whisk your egg whites until foamy with uniform small bubbles. Add in your remaining sugar and beat on high speed until stiff peaks form.
Fold your egg whites into your chocolate mixture. Fold in your whipped cream until just combined. evenly distribute your mousse into four separate containers or ramekins. Cover each with plastic wrap and chill in the fridge until firm, about 2 hours. Enjoy!
