Method

1. Whisk sugar and egg yolks until thick and creamy. Add vanilla pod or essence, then pour in cream in a steady stream.
2. Place the mixture (custard) in the top of a double boiler over simmering water and stir with a wooden spoon until the mixture coats the spoon, about 20 minutes. Stir all over the base and sides of pan to incorporate all the mixture. Immediately the custard thickens, remove from the stove. Remove the vanilla pod, if using.
3. Allow to cool, then transfer the custard to a shallow ovenproof dish or 4 ramekins (125 ml capacity) and refrigerate overnight to chill thoroughly.
4. Heat the grill until extremely hot.
5. Cover the chilled custard with a thick, even layer of castor sugar (see tips) and immediately place under the hot grill.
6. Grill until the sugar melts and forms a fine, crisp, golden brown layer. Watch sugar carefully, to make sure it doesn't burn.
7. Remove the dish(es) from the oven and place in a sink or bowl of cold water or ice to cool. Wipe the base(s) dry and serve: crack the crust carefully to get to the cream underneath.