Score the skin of the mangosteen right around. Remove the stem and scoop the flesh out of the skin with a spoon. Remove the stone. Set the skins aside and rinse with water. Purée the flesh in the blender or with the hand blender. Sieve the mangosteen purée.
Place the sugar and the coconut cream in a saucepan and bring to the boil. Remove from the heat and add the squeezed gelatine. Stir until the gelatine completely has dissolved. Pour into the mangosteen purée. Beat the cream with the mixer until it is thick. Gently fold through the mangosteen purée. Transfer to the fridge for 30 minutes to firm. Spoon the mousse into a piping bag with a serrated nozzle and leave to firm for 2.5 hours.
Pipe the mousse into the the mangosteen shells and garnish with the edible flowers.
