This amazingly simple dessert is more or less the same as the Spanish/Catalunian Crema Catalan. It's a set egg custard with a crunchy caramelised sugar topping.
In a heatproof bowl, mix together the yolks and caster sugar. When the cream begins to boil, pour it over the egg/sugar mixture and stir well to combine them. Place 3 ramekins in a deep-sided roasting tray. Pour hot water into the tray so that it comes to two-thirds of the way up the ramekins. Divide the custard mix between the ramekins and put it all in the oven for 40 minutes. After this time the custards should be set with only a very slight wobble. Remove from the bain marie and allow to cool to room temperature.