01 - Preheat oven to 325°F. Lightly grease a 2-quart baking dish with butter.
02 - Rinse short-grain rice thoroughly under cold water until the water runs clear, then drain well.
03 - In a large mixing bowl, whisk together sweetened condensed milk, whole milk, melted butter, granulated sugar, vanilla extract, ground cinnamon, and salt until fully blended.
04 - Stir in rinsed rice and raisins, if using, ensuring ingredients are evenly incorporated.
05 - Pour the mixture into the prepared baking dish and gently stir to distribute rice throughout.
06 - Bake uncovered for 1 hour, stirring gently every 20 minutes, until the pudding is set and the top turns lightly golden.
07 - Remove from oven and allow to cool slightly. Serve warm or chilled, topped with additional cinnamon if desired.