In a medium mixing bowl, combine the heavy cream, cocoa powder, erythritol, vanilla extract, and salt. Whisk together until the mixture is smooth and fully combined.

1. Using an electric mixer or a hand whisk, beat the mixture on medium-high speed for about 3-5 minutes until soft peaks form. Be careful not to overbeat it, as it can turn into butter.
2. If desired, fold in the chopped dark chocolate to add an extra layer of richness and texture.
3. Spoon the mousse into individual serving cups or bowls. Chill the mousse in the refrigerator for at least 1-2 hours to allow it to firm up.
4. Once chilled, serve the mousse as is, or garnish with whipped cream, raspberries, or a sprinkle of cocoa powder.