Preheat the oven to 170 ºC (325 ºF). In a saucepan, heat the cream for 5 minutes with the vanilla bean cut in half, without boiling, just to infuse the vanilla. Scrape out the vanilla seeds and combine with the milk. If you are not using a vanilla bean, simply add the vanilla extract to the hot cream.
In a bowl, whisk together the egg yolks and sugar. Stir in the hot cream. Pour the mixture into four 180 ml (3/4 cup) crème brûlée dishes or ramekins.
Bake in a water bath. To do this, place the custard dishes in a baking dish. Pour hot water 3/4 up the sides of the dishes. Bake for 40 minutes.
Let cool and refrigerate to chill completely. Sprinkle with the additional sugar and caramelize quickly with a crème brûlée iron or a torch. You could also caramelize the crème brûlée under the broiler of a very hot oven. Serve immediately.