Preheat the oven: Set your oven to 150°C (300°F). Grease an ovenproof dish (approximately 20x25cm) with butter.
Prepare the rice: In a large saucepan, melt the butter over medium heat. Add the pudding rice and stir it around for 1-2 minutes to coat the rice with the melted butter.
Add the milk and cream: Pour in the full-fat milk and double cream. Stir to combine, then add the sugar, vanilla extract, and a pinch of salt. Mix well.
Cook the rice mixture: Bring the mixture to a gentle simmer, stirring occasionally. Once it begins to simmer, reduce the heat to low and allow it to cook for about 5 minutes, stirring frequently.
Transfer to the oven: Pour the rice mixture into the prepared ovenproof dish. Smooth the top with a spatula. Grate a little nutmeg over the top of the pudding to add a lovely, aromatic flavor.
Bake the pudding: Place the dish in the preheated oven and bake for 1.5 to 2 hours. Stir the pudding every 30 minutes to ensure it cooks evenly. The pudding is done when the rice is tender and the mixture has thickened to a creamy consistency.
Serve: Once baked, remove the rice pudding from the oven and let it cool slightly before serving. You can enjoy it warm or cold, depending on your preference.