01 - Preheat the oven to 325°F. Lightly grease a 2-quart baking dish with butter.
02 - Rinse the short-grain rice under cold running water until the water runs clear. Drain well.
03 - In a large mixing bowl, whisk together the sweetened condensed milk, whole milk, melted butter, granulated sugar, vanilla extract, ground cinnamon, and salt until well blended.
04 - Stir the rinsed rice and optional raisins or sultanas into the mixture.
05 - Pour the prepared mixture into the greased baking dish. Distribute the rice evenly with a gentle stir.
06 - Bake uncovered for 1 hour, stirring gently every 20 minutes, until the pudding is set and the surface is lightly golden.
07 - Remove from the oven and let cool slightly. Serve warm or chilled, finishing with a sprinkle of ground cinnamon if desired.