Open both cans of coconut milk and poke a hole into the cream with a knife, going down to the bottom of each can. Drain off the separated coconut water and take 2 tablespoons. Put the rest into your next smoothie!
Heat the chocolate, 2 tablespoons of coconut cream, and 2 tablespoons of the separated coconut liquid in a double boiler, stirring occasionally, until melted and smooth. Chill remaining solid coconut cream until ready to serve
Beat aquafaba, lemon juice, and a pinch of salt in a bowl using an electric mixer on medium-high speed until stiff peaks form and the mixture is tripled in volume, 7–8 minutes
Using a rubber spatula, gently fold about one-quarter of whipped aquafaba into chocolate mixture until incorporated. Fold in remaining whipped aquafaba in 3 more additions until incorporated and no streaks remain
Divide the mousse among ramekins and chill until set, at least 2 hours
Using an electric mixer on medium-high speed, beat the reserved chilled coconut cream, and a pinch of salt in a medium chilled bowl until soft peaks form 3–4 minutes
Dollop the mousse with the whipped coconut cream and some grated chocolate