Dice 1 mango and combine with the mint. Divide almost half the mango mixture between 4 small bowls, reserving a little for the topping.
Purée the remaining mango with the lime juice in a food processor or blender.
Beat the cream in a bowl until just holding soft peaks, then stir in the yogurt. Fold the cream mixture into the mango purée and swirl to marble.
Divide the cream mixture between the bowls and top with the reserved diced mango. Halve each passion fruit, then scoop the seeds of each half over each fool. Chill in the refrigerator until ready to serve.