Line the bottom and sides of 23cm spring form tin with parchment paper. Mix together the ginger nut biscuit crumbs and the butter and tip in to the bottom of the lined tin and up the sides. Using the back of a wooden spoon push the biscuit base down so it compacts. Put the base in fridge to firm up for 15 minutes or so.
For the cheesecake mixture, put the Philadelphia into a bowl with the cream, caster sugar and the vanilla and beat until smooth with an electric hand-held mixer.
To make the salted caramel, beat the salt into the caramel until smooth. Remove tin from fridge and spread two-thirds of the caramel on to the base. Then add cheesecake mixture and carefully spread on top, smoothing it off nicely with the back of a spoon.
Place tin in fridge for 2 hours or overnight to set. Once set, remove from the fridge and scatter popcorn and pecan nuts on top, drizzle over the rest of the salted caramel to serve.