Place milk, cream and vanilla pod and seeds in a pan and bring to just below boiling point. Set aside for 1 hour for the vanilla flavour to infuse.
Meanwhile, halve passionfruit and scrape pulp into a sieve set over a bowl. Push juice through sieve with a wooden spoon (you need about 150ml of juice).
Preheat the oven to 120°C.
Whisk together egg yolks and caster sugar in a bowl until well combined. Strain the milk mixture over the yolk mixture, then stir in passionfruit juice. Pour mixture into eight 175ml ramekins and place in a baking dish. Pour hot (not boiling) water into the dish to come halfway up the sides of the ramekins. Bake for 50-60 minutes until just set but still slightly wobbly in the centre. Remove ramekins and leave to cool, then cover and chill overnight.For passionfruit jellies, pulp and sieve passionfruit as before. Peel away the thin membrane lining of 16-20 of the half-shells, then place shells in empty egg cartons ready for filling. Combine passionfruit juice, sugar and 1/2 cup (125ml) water in a small pan and warm over low heat to dissolve sugar (don’t allow it to get too hot). Meanwhile, soak gelatine in a bowl of tepid water until soft, then squeeze out excess water. Add leaves to passionfruit mixture and stir until dissolved. Fill shells with jelly mixture and chill in the fridge until set.
Just before serving, dust tops of each creme brulee with 1 teaspoon of icing sugar and, holding a kitchen blowtorch about 10-12cm away from the surface, caramelise sugar evenly. Alternatively, place ramekins on a tray under a hot grill for 2-3 minutes to caramelise sugar. Leave tops to harden for a few minutes, then serve immediately with jellies.