Get the juice of cooked chickpeas and reduce it to 2/3 cup.
Pour it into a large mixing bowl and add the cream of tartar.
Beat the liquid like you would with egg whites.
Add the sugar while beating, and then place it in the fridge while preparing the chocolate.
Put the chocolate in a pan with the vanilla extract and melt on low heat, mixing constantly.
If too dry, add milk and keep mixing until all melted.
In a large mixing bowl, use a spatula to fully mix the chocolate with 1 big spoonful of your chickpea whites.
Repeat the process very delicately until all the whites have been folded into the chocolate.
Pour the mousse evenly into 6 ramekins.
Place in the fridge for at least 6 hours before serving.