Melt the chocolate chips over a double boiler on the stove-top. To set up a double boiler, bring a small pot of water to a simmer and place a heatproof bowl over the pot, ensuring the bottom of the bowl does not touch the water. Add the chocolate chips to the bowl and stir occasionally. The chocolate should melt and become smooth in about 5-7 minutes.
Let the melted chocolate cool for 5 minutes, then transfer it to a high-powered blender. Add the silken tofu, cream or milk, sugar, vanilla, and salt. Blend until the mixture is very smooth, scraping down the sides as needed.
Pour the mousse into glass jars or serving dishes and refrigerate until ready to serve. Ideally, let it chill for at least an hour so it can firm up.
Top with optional vegan whipped cream and fresh fruit before serving.