Preheat the oven to 140C/285F/Gas 1.
Melt the butter in a heavy-based casserole dish over a medium heat. Add the rice and stir to coat. Add the sugar, stirring until dissolved. Continue stirring until the rice swells and becomes sticky with sugar.
Pour in the milk and keep stirring until no lumps remain. Add the cream and vanilla and bring the mixture to a simmer. Once this is reached, give the mixture a final stir and grate at least a third of a nutmeg over the surface. Bake for 1-1½ hours and cover with foil if the surfaces browns too quickly.
Once there is a thin, tarpaulin-like skin on the surface, and the pudding only just wobbles in the centre, it is ready. Serve at room temperature.
I like my rice pudding plain, but you can add fruit, raisins or jam to the mixture.