Pour 3/4 of the puree into a small bowl and sprinkle the gelatin over the surface to soften. In a small saucepan, heat the remaining 1/2 cup of puree and the sugar over low heat until the sugar dissolves. Stir the puree and gelatin into the warm puree and stir to dissolve the gelatin. If lumps remain, put the pan over low heat and stir just until the lumps dissolve. Pour the mixture through a fine-mesh strainer into a large bowl. Let the mixture cool to room temperature. In a stand mixer fitted with the whisk attachment, whip the cream until it holds medium peaks. Fold one-third of it into the coconut mixture. Fold in the remaining whipped cream until no streaks remain. Pour the mousse into a bowl (or ramekins) and store in the refrigerator for up to 3 days.
Reprinted with permission from Miette by Meg Ray with Leslie Jonath, Chronicle Books copyright (c) 2011