01 - Preheat oven to 325°F. Lightly grease a 2-quart baking dish with butter.
02 - Rinse rice under cold water until the water runs clear. Drain thoroughly.
03 - In a large bowl, whisk together condensed milk, whole milk, melted butter, granulated sugar, vanilla extract, ground cinnamon, and salt until blended.
04 - Stir in the rinsed rice and, if desired, raisins or sultanas until evenly combined.
05 - Pour mixture into the prepared baking dish and stir gently to evenly distribute rice throughout the liquid.
06 - Bake uncovered for 1 hour, stirring gently every 20 minutes, until the pudding is set and the top is lightly golden.
07 - Remove from oven and let cool slightly. Serve warm or chilled, topping with extra cinnamon if desired.