Add the aquafaba to a stand mixer. Whip on high speed for 5-10 minutes, or until it reaches stiff peaks. This step might take a while, so be patient.
In the meantime, add the coconut cream, hazelnut butter, coconut sugar, cacao powder, vanilla, and salt, to a mixing bowl. Whisk until fully combined. The sugar and cacao powder should be fully dissolved. If you want to save time, you can add all of the ingredients to a small blender and blend until smooth.
Transfer the whipped aquafaba to a large mixing bowl. Pour in half of the coconut cream mixture and fold it gently using a spatula. Once it is almost combined, add the remaining coconut cream mixture and fold again until you don't see any white aquafaba left. The aquafaba will deflate, and you will end up with an almost liquid consistency, which is normal.
Immediately pour into 3 small ramekins and refrigerate for at least 4 hours, or preferably overnight. The mousse will harden as it cools.
Top with roasted hazelnuts and shaved chocolate, and enjoy chilled!