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, granulated sugar, vanilla extract, ground cinnamon, and salt.
04 - Stir rinsed rice and raisins or sultanas (if using) into the milk mixture.
05 - Pour mixture into prepared baking dish and gently stir to distribute rice evenly.
06 - Bake uncovered for 1 hour, stirring gently every 20 minutes, until set and surface is lightly golden.
07 - Remove from oven and cool slightly. Serve warm or chilled, sprinkling with extra cinnamon if desired.