Reduce chickpea water by one third by boiling and simmering for about 5 minutes. Allow to cool.
Whisk chickpea water and cream of tartar until stiff peaks form. Add sugar and whisk until peaks are stiff.
Mix melted chocolate, margarine, sugar, and vanilla until smooth.
Combine one third of the aquafaba with the chocolate mix, then fold in the remaining aquafaba gently.
Pour mixture into serving dishes and refrigerate for at least 2 hours.
Dust with cocoa powder and garnish with mint before serving.
