In a small pot, combine sugar or sweetener with 1 cup of water.
Bring to a boil and continue to cook, whisking continuously until sugar is dissolved.
Set simple syrup aside to cool.
Melt dark chocolate in a microwave, stirring every 30 seconds, for about 60-90 seconds until glossy and smooth.
In a blender, combine simple syrup, drained tofu, melted chocolate, vanilla, and salt.
Blend, scraping down the sides of the blender as needed, for a minute or so until completely smooth.
Pour mousse mixture evenly into 6 ramekins, place on a small baking sheet or large plate, and chill for at least 1 hour.
When ready to serve: Top with coconut whipped cream, or regular whipped cream and a sprinkle of cocoa powder.
These will keep for a week or more in the fridge.