Heat the oven to 170°C (or whatever temp your roast is at)
Use the butter to grease a shallow 750 ml ovenproof dish, about 4 cm deep. Add the milk, cream, rice, vanilla and sugar to the dish and stir to mix. Cover with foil
Bake in the oven for around 1½ hours or until the rice is cooked. *see notes on time
Remove the foil and turn the oven setting up to 180ºC. finely grate a light coating of nutmeg over the top of the pudding. Bake for a further 30 minutes, or until the rice is soft and a golden brown skin has formed. Serve on its own, with ice cream, fruit or homemade jam.