Pour the aquafaba (water from the chickpea tin) into a blender. Whisk at full power for 5 minutes until it forms a white liquid. Add the maple syrup in half way through. Don’t worry if soft peaks don’t form, it will firm up over time.
Pour into a bowl, and gently fold in the melted chocolate. Mix well.
Pour into your mouse glass and leave to stand for 5 minutes. Once it has begun to set, sprinkle over your pistachios and cacao nibs (or other toppings of choice).
Pop in the fridge for at least an hour, and it will form a mousey texture. Enjoy!