01 - Set oven to 325°F. Lightly grease a 2-quart baking dish with butter.
02 - Rinse short-grain rice under cold water until water runs clear, then drain thoroughly.
03 - In a large mixing bowl, whisk together condensed milk, whole milk, melted butter, granulated sugar, vanilla extract, cinnamon, and salt until well blended.
04 - Add rinsed rice and, if desired, raisins to the milk mixture. Stir to combine evenly.
05 - Pour the prepared mixture into the greased baking dish, ensuring rice is distributed evenly throughout.
06 - Bake uncovered for 1 hour, stirring gently every 20 minutes to prevent sticking. Continue until the pudding is set with a lightly golden surface.
07 - Remove baking dish from oven and allow to cool slightly. Serve warm or chilled, garnished with additional cinnamon if preferred.