Break the chocolate into smaller chunks and melt it very slowly over a water bath or low intensity in the microwave. (I set it at Power 4 for approximately 3 minutes. Stir every minute.) Let cool. 

Open your can of chickpeas and drain the chickpea water into large glass bowl. The bowl and the utensils you’ll use to whip aquafaba need to be completely grease-free as even the tiniest grease residue can prevent aquafaba from reaching stiff peaks. One 400 g tin should give you 240 ml / 1 cup of chickpea water. Reserve the chickpeas for another use, like the chicken recipe or the brownie recipe below. 

Adding a teaspoon of acid (like lemon juice) to the chickpea water will speed things up and stabilize the foam. 

Using an electric egg whisk, whip the chickpea water into stiff peaks – this is super important. The best way to check if you have achieved stiff peaks is to invert the bowl with whipped aquafaba. If aquafaba slides down even a tiny bit, you are not there yet – keep on whipping until it does not move at all. Takes about 15 minutes. Aquafaba cannot be overwhipped. 

Check that the chocolate has cooled down sufficiently – it should not be warm to the touch or else chocolate may seize and you will end up with grainy mousse.

Gently fold melted chocolate and optional maple syrup into whipped aquafaba using a silicone spatula. Do not worry if your fluffy mixture deflates once the chocolate has been added – that’s perfectly normal. By the time you’ve added all of your melted chocolate, the mousse may have more of a pourable consistency. 

Divide the mixture between 4 glasses. Gently stir the mixture between putting it into individual glasses as a bit of melted chocolate tends to drop to the bottom sometimes. (I used small mason jar. Divide evenly.) 

Put glasses into the fridge for minimum 3 hours for the mousse to set. You can chill overnight and it’s perfectly set and fluffy each time.