Preheat oven to 160°C/140°C fan-forced. Place cream in a saucepan over medium heat. Cook for 10 minutes or until heated through (do not boil).
Meanwhile, whisk egg yolks, orange rind and 1/3 cup sugar in a heatproof bowl until thick and creamy. Gradually whisk in hot cream. Return mixture to clean saucepan. Cook, stirring, over medium-low heat for 10 minutes or until mixture thickens slightly and coats the back of a wooden spoon. Pour mixture into four 3/4 cup-capacity flameproof ovenproof ceramic dishes.
Place dishes in a large baking dish. Pour boiling water into baking dish until halfway up side of dishes. Bake for 20 minutes or until custard is just set (mixture may wobble slightly in centre, but will firm on standing). Cool. Refrigerate overnight.
Preheat grill on high. Place dishes in a large baking dish. Arrange ice cubes around dishes. Combine passionfruit pulp and remaining sugar in a bowl. Spoon over top of custards. Grill for 3 to 5 minutes or until sugar has melted and turned golden. Serve.