Whisk egg yolks, water, and half the sugar in a saucepan over low heat for 10 minutes until thickened.
Whisk the mixture in a bowl until cool, light, and fluffy.
Blend mango flesh until smooth and pass through a sieve.
Whisk cream into the mango until soft peaks form, then fold in the egg yolk mixture.
Whisk egg whites with remaining sugar until stiff and glossy.
Fold the egg white mixture into the cream mixture.
Spoon into cling film-lined moulds and freeze for 1 to 2 hours.
Preheat oven to 100°C.
Whisk 2 egg whites for the meringue until soft peaks form.
Add sugar and whisk until stiff and glossy.
Pipe 18 circles of 7.5cm diameter onto baking parchment.
Bake for 20 minutes, then leave in the turned-off oven for 2 hours to cool.
Remove parfait from the freezer 5 minutes before serving.
Stack three meringue discs per plate, layering with whipped cream and passion fruit.
Plate the parfaits, dust meringues with icing sugar, and garnish with mango slices.