Melt milk chocolate and dark chocolate in a water bath and let cool for a while.
Whisk the chickpea brine in a clean ceramic or glass bowl with a hand mixer for 5-10 minutes or until the brine has turned into a thick white fluff, which doesn't drip from the edges when you turn the bowl upside down.
If you're using chickpea brine with salt, you might want to whisk some sugar in the brine to make it sweeter.
When the melted chocolate has cooled down mix it into the fluffy aquafaba until you get a chocolatey fluff. This is best done with a silicone spatula / spoon. Note: the aquafaba is not as fluffy as before when adding the chocolate, but it will be more mousse like when you let it set in the fridge.
When the aquafaba and chocolate is thoroughly combined put it in a glass container or bowl and cover it. Let set in the fridge for at least three hours, preferably overnight.
Although not pictured here, this mousse tastes best with plant-based whipped cream. And of course you can add berries on top too :)