Drain the liquid from the chickpeas. This should be about 3/4 - 1/2 cup of liquid. Add to a large bowl with the cream of tartar. Whisk for 5 minutes continuously until its thick and fluffy.
Add the sugar. Whisk for another 5 minutes until the aquafaba forms stiff peaks.
Malt the chocolate in a bain marie or slowly in a microwave (10-15 seconds then mix, repeat until melted).
Pour into the aquafaba and add the milk. Fold them together to form a thick mousse. Its important to fold as mixing will knock the bubbles out of the mousse. Add a handful of cacao nibs or chocolate drops. Fold in then spoon into ramekins.
Sprinkle the top with nibs/drops and refrigerate for 1 hour (minimum). Serve straight from the fridge. Enjoy!
TIP: Use unsalted aquafaba. I served it into two lager bowls but this could easily serve 4 into smaller ramekins. Use dark chocolate as I found the milk chocolate version wasn't as rich.