First remove 6 tablespoons of the milk, boil the rest with the rice. Simmer over low heat until the rice pudding is cooked. Stir again and again so that nothing sticks.
Meanwhile, mix the custard powder with the remaining milk and sugar. When the rice pudding is ready, remove from the heat and stir in the mixed pudding powder.
Bring everything to the boil again briefly. Arrange the rice pudding in a bowl and sprinkle the vanilla rice pudding with cinnamon or cocoa powder.