Preheat the oven to 140C/275F/Gas 1.
Beat together the egg yolk & sugar in a bowl until fluffy. Add the vanilla essence and cream and mix.
Melt the chocolate in a bowl in the microwave and when completely liquid add the chocolate to the egg mixture, whisk quickly to blend to a gorgeous dark emulsion.
Place the chopped ginger into the bottom of the ramekins. Top with the chocolate mixture. Place the ramekins into a deep roasting tin and pour in enough hot water to come up to at least two-thirds up the side of the pots. Bake for around 30 minutes, or until a crust forms on the top and it feels slightly springy to the touch.
Remove the pots from the oven, allow to cool a little before extracting the pots from their water bath. Chill in the fridge for as long as you can bear (ideally at least six hours, one hour minimum) before serving.