Drain the chickpeas, retaining the liquid (aquafaba). (Cover and refrigerate the chickpeas and use them later for a salad or hummus, for instance). Pour the aquafaba into the blender and beat until a white, snow-like consistency is reached. Melt the chocolate in a bain-marie, stir in the agave syrup. Using a wooden spoon, carefully fold the chocolate into the aquafaba snow.
To serve & decorate
Place the coconut milk in the fridge overnight. Remove the "hard" part of the coconut milk from the can, beat until frothy using the whisk on a hand mixer. Divide the chocolate mousse into glasses, decorate with the coconut foam. Refrigerate for at least 1 hr.