In a medium saucepan, heat the cream, vanilla pod and seeds, grated ginger and salt just to the boil, then turn off the heat and leave the mixture to steep for at least an hour - the longer the better.
Melt the chocolate either using a microwave (medium heat, 30 second bursts) or in a bowl set over a pan of boiling water. Leave to cool slightly.
Preheat the oven to 140c. When the cream is ready and while the chocolate is cooling, in a separate bowl gently whisk together the yolks and sugar until smooth, trying not to add too much air to the mixture. Add the cooled cream and gently whisk to combine. Add the lukewarm (but still fluid) chocolate and gently combine. Pour the whole mixture through a sieve and into a jug.
Set six ramekins (I used wide, shallow ramekins to maximise the amount of caramel topping) in a tall-sided baking dish. Pour the custard mixture into the ramekins and place the dish in the oven. Slowly pour water into the baking dish, enough to come up about two-thirds of the way. Bake for about 45 minutes - the actual time will depend on your oven and the size and shape of your ramekins. They are ready when the edges are set and the centre is still jiggly.
Cool on the counter, then refrigerate until firm and fully set, at least four hours. Once they are completely chilled, cover each custard with plastic wrap.
When you are ready to eat them, add about a teaspoon of Demerara sugar to the top of each ramekin and tap to distribute the sugar evenly across the top. Melt the sugar with a blow torch (a grill is not going to cut it!) and return to the fridge for about half an hour to make sure the custard is completely re-chilled.