Special equipment: 4 ramekins (about 1 cup/9fl oz/250ml capacity) or 6 shallow dishes
Preheat the oven to 300 degrees F (150 degrees C).
Put the ramekins in a roasting pan along with enough hot water to come halfway up their sides. Put the cream, mascarpone, and vanilla in a pan and heat until almost boiling, then remove the pan from the heat and add the ginger.
In a small bowl, whisk the egg yolks and sugar together until they are pale and fluffy. Gradually add the ginger cream, whisking all the time. I like to include the bits of ginger in the creme brulee, but if you don't want them, place a strainer over a measuring pitcher and pour the cream mix into it to strain out the ginger. Using a wooden spoon, push the ginger mix left in the strainer to get as much flavor as you can, then discard the ginger bits.
Pour the cream mix equally into the shallow dishes, then place them (still in the roasting pan) in the oven for about 30 minutes, (if you have used ramekins, they may take slightly longer) or until the brulees begin to set. They should still wobble like jelly in the very center but should not be too liquid, nor completely set. It is very easy to overcook these, so check after 20 minutes to see how they are doing. Then check every 5 minutes after that, as some ovens are much more powerful than others.
Remove the brulees from the oven and from the roasting pan and let cool right down, then place in the refrigerator for at least 1 hour. This is a brilliant dish for entertaining as you can make them to this stage, then keep in the refrigerator and finish them just before you're ready to serve.
Sprinkle about 1 tablespoon of brown sugar evenly on the top of each brulee, making sure the tops are completely covered. Using a cook's blowtorch, caramelize the sugar until dark brown and crisp. A very hot broiler works okay too, but a blowtorch is more fun. Let cool a little and then serve immediately.