Begin by melting the dark chocolate. You can do this in a heatproof bowl over simmering water or use the microwave. Ensure it's smooth and without lumps.
In a separate saucepan, warm the coconut milk over medium heat, but don’t let it boil.
Once warm, whisk in the cocoa powder, ensuring there are no lumps.
Add the melted chocolate to the coconut milk and stir until combined.
Stir in the agave syrup, vanilla extract, and a pinch of salt.
Once mixed thoroughly, pour the mousse into individual serving glasses or bowls.
Chill in the refrigerator for at least 2 hours, or until set.