01 - Preheat oven to 325°F. Grease a 2-quart baking dish lightly with butter.
02 - Rinse uncooked rice thoroughly under cold water until water runs clear; drain well.
03 - In a large mixing bowl, whisk together condensed milk, whole milk, melted butter, granulated sugar, vanilla extract, ground cinnamon, and salt until fully combined.
04 - Stir rinsed rice and, if desired, raisins into the milk mixture.
05 - Pour the mixture into the prepared baking dish, then gently stir to evenly distribute the rice.
06 - Bake uncovered for 1 hour, gently stirring every 20 minutes, until pudding is set and the surface is lightly golden.
07 - Remove from oven and let cool slightly. Serve warm or chilled, dusted with additional cinnamon if desired.