Chill the coconut cream in the fridge at least one day in advance to allow it to solidify and separate the solid from the liquid.
Spoon the solidified portion of the coconut cream out into a large bowl along with the powdered sugar. Use an electric mixer to whip the coconut cream until light and smooth, about 2-3 minutes. Reserve a couple spoonfuls of the whipped coconut cream to top the mousse if desired.
Add the melted chocolate and whip another 1-2 minutes, until fluffy and a mousse-like consistency. Gently fold in the pudding.