01 - Preheat oven to 325°F. Lightly grease a 2-quart baking dish with butter.
02 - Rinse rice under cold water until water runs clear. Drain thoroughly.
03 - In a large mixing bowl, whisk together sweetened condensed milk, whole milk, melted butter, sugar, vanilla extract, cinnamon, and salt until fully combined.
04 - Stir rinsed rice and optional raisins into the milk mixture, mixing until evenly distributed.
05 - Pour mixture into prepared baking dish and gently stir to ensure rice disperses uniformly throughout.
06 - Bake uncovered for 1 hour, gently stirring every 20 minutes. Continue until pudding is set and surface develops a light golden color.
07 - Remove from oven, allow to cool slightly, and serve warm or chilled. Sprinkle with extra cinnamon if desired.