In a steam oven, put the rice, sugar and milk in an unperforated dish and cook for an hour at 100°.
On the hob, bring some water to the boil and pre-cook the rice in it for 2 minutes. Drain it.
Put the rice in with the milk and sugar. Cook for an hour (be sure to lower the heat once it boils so the milk doesn’t boil over!).
Pour the rice into a bowl, add the chocolate (one heaped tbsp if you want a light chocolate taste, 2 tbsp if you’d like it more pronounced), the raisins and the coarsely chopped toasted hazelnuts.