Heat oven to 350ºF (175ºC)
Butter the inside edge (no need to do the bottom) of a baking dish, then add the rice and the milk and cream (if using).
Now add the sugar, and stir until it dissolves.
Add a pat of butter, and a little sprinkle of nutmeg.
Place the dish in the center of the pre-heated oven, and set the timer for 30 mins.
After 30 minutes, take the dish out of the oven, stir well, and return it to the oven. Set the timer for another hour.
Check the pudding after an hour, and you may have to break the skin to check the rice. Continue to cook for up to another half hour, if necessary. The rice pudding is ready when it has started to thicken (it won't be runny).
Remove the rice pudding from the oven, and let cool slightly before serving. Spoon into dishes, and serve with a dash of cinnamon, if desired.