01 - Preheat oven to 325°F. Lightly grease a 2-quart baking dish with butter.
02 - Rinse the rice under cold water until the water runs clear; drain thoroughly.
03 - In a large mixing bowl, whisk together condensed milk, whole milk, melted butter, granulated sugar, vanilla extract, ground cinnamon, and salt until fully incorporated.
04 - Add the rinsed rice (and raisins, if using) to the bowl. Stir gently to combine.
05 - Pour the combined mixture into the prepared baking dish. Gently stir to ensure even distribution of rice and fruit.
06 - Place uncovered dish in oven. Bake for 1 hour, gently stirring every 20 minutes, until set and the top is lightly golden.
07 - Remove from oven and allow to cool slightly. Serve warm or chilled. Sprinkle with additional cinnamon if desired.