Put the milk into a pan on a low heat and infuse with the cinnamon and citrus peel until steaming – around 15–18 minutes. The more slowly you steam it, the more flavourful it will be. Turn off the heat and leave to cool, then pass through a sieve.
Wash the rice in cold water to get rid of as much of the starch as possible – the water should run clear.
Add the butter and cream to the infused milk, put back on a low heat and let the butter melt, then add the sugar and cook until dissolved. Add the rice and continue stirring on a low heat for a minimum of 30 minutes, until the rice is cooked and looks creamy. Cooking it on a low heat should keep it liquid – if it starts to dry out a bit, add an extra splash of milk.
Serve warm, dusted with ground cinnamon. If serving cold, leave to come to room temperature, then spoon into glasses or cups, dust generously with ground cinnamon and refrigerate.