Brush the truffle clean then using a sharp knife, finely chop it; split the vanilla bean lengthwise;
Break the eggs and separate the whites and the yolks into two different bowls; beat the yolks with the sugar until the mixture becomes white and foamy;
In a saucepan, boil the cream with the two halves of the vanilla bean; as soon as it starts to boil, remove the vanilla bean halves; proceed to pour the cream into the egg and sugar bowl and beat the mixture; slowly incorporate the chopped truffle;
Preheat the oven to 120o C; fill each custard cup with the truffle and vanilla cream; place the cups on a baking tray filled with water; cook for 1 hour, occasionally adding water to maintain the original water level;
Once removed from the oven, let the cremes cool down, then set the oven to broil; sprinkle their tops with powdered sugar and quickly put them in the oven so that their tops carmelize (this should not take very long);
Crèmes brûlées are served hot or slightly cooled.
Source : Le meilleur de la truffe