"So... you are making hummus or some other dish with chickpeas and you are just wasting the chickpea water? How dare you! Didn't you know it can form the basis of some the most delicious, light, and foamy vegan ice creams and mousses?
I didn't know either but since Lina told me about it I am never going to waste a drop of chickpea water again."
Melt chocolate in top of a double boiler over simmering water, stirring frequently and scraping down the sides with a rubber spatula to avoid scorching. Let cool slightly, about 10 minutes.
Pour aquafaba into the bowl of a stand mixer fitted with a whisk attachment. Beat on high speed until fluffy and quadrupled in volume, about 1 minute. Add xanthan gum and beat for 30 seconds. Add confectioners' sugar and vanilla sugar; continue beating until foam is firm and glossy, about 2 minutes more.
Fold melted chocolate gently into whipped foam until thoroughly incorporated. Transfer to a lidded container.