To turn a fruit curd into a fruit mousse, fold in whipped cream. If you’re not using the mousse right away and serving it within a day, add gelatin as we do here to keep it from separating. Note: Whenever you combine tropical fruit with gelatin, bring the tropical fruit puree to a simmer before you add the gelatin. This kills protease enzymes that would otherwise interfere with the gelatin setting. This mousse can be used to make napoleons.