The day before make the sorbet. Put the water and sugar in a small saucepan on a low heat and stir gently until all the sugar has dissolved. Leave to cool.
Put the sugar syrup in a blender with the juice of a lemon. Scoop out all the passionfruit flesh and add to the blender. Pulse gently to help seperate the seeds from the fruit. Now pass the whole mix through a seive and discard the seeds.
Put ¾ of the mix into a plastic tub and put into the freezer. Check after a few hours and once the mix has almost frozen break it up with a fork and put back in the freezer. Check and mix with a fork again after two hours and then leave overngiht to properly set.
Place the rest of the passionfruit mix in the fridge to use the next day to make the passion fruit topping for the cheesecakes.
To make the cheesecakes first crush the biscuits. Melt the butter and mix with the biscuit crumbs. Grease four 9cm rings with a little butter and put them on a plate or baking sheet. Using the back of a spoon push the biscuit base mix into a flat layer at the bottom of each ring and them put them in the fridge for an hour to firm up.
To make the vanilla filling first whip the double cream. Now gently mix in the icing sugar, cream cheese and vanilla extract. If you wish you can add a little lemon juice here too if you like your dessert slightly less sweet.
Add the cream cheese on top of the biscuit bases. Don't fill the moulds all the way to the top as you need to keep room for the jelly layer. Smooth as much as you can and put back into the fridge for a couple of hours.
Mix the gelatine with three tablespoons of warm water to help it dissovle. Gently reheat the rest of the passionfruit in a small pan and then take off the heat and stir in the gelatine. Leave it to cool and then pour on top of the cheesecakes. Back into the fridge for a final set, until the jelly topping is firm.
To serve gently push each cheesecake out of it's ring and place on a plate. Add a scoop of sorbet and enjoy.