1. Sprinkle the cornstarch over 1 cup milk in a bowl and stir to dissolve. Bring the remaining 3 cups milk just to a boil over medium heat. Whisk the hot milk into the cornstarch mixture then return to the saucepan and stir over medium-low heat until the mixture simmers. Reduce the heat to very low and simmer gently for 5 minutes. Stir in the sugar.

2. Rinse the molds with cold water. Cut 3 of the passion fruit in half, scoop out the seeds, and rub through a sieve over a bowl, discarding the seeds. Stir into the cornstarch mixture, then divide among the molds. Press a piece of plastic wrap directly on the surface of each pudding. Refrigerate for at least 2 hours or until set.

3. Briefly dip the bottom of each mold in a bowl of hot water. Unmold each onto a dessert plate. Cut the remaining 5 passion fruit in half, and spoon equal amounts of the fruit over the puddings. Serve chilled.