In a heatproof bowl set over (or in) a gently simmering pot of water, melt the chopped dark chocolate, stirring occasionally until smooth. Remove from heat and let cool slightly.
In a blender, combine the drained silken tofu, melted chocolate, maple syrup, peanut butter, vanilla extract, and salt. Blend on high until completely smooth, about 1 minute.
Divide the mousse evenly among four serving glasses or ramekins. Cover each with plastic wrap and refrigerate for at least 2 hours, until set and no longer runny.
Can be prepared up to 24 hours in advance—keep chilled until ready to serve.
