In a medium saucepan, combine short-grain rice with 1 cup of water. Bring to a rolling boil over medium-high heat, then reduce to low, cover, and simmer for about 15 to 18 minutes until rice is tender and all water is absorbed.

Preheat your oven to 350°F (175°C). Grease the 9x9-inch baking dish with butter.

In a large mixing bowl, whisk together sweetened condensed milk, whole milk, granulated sugar, eggs, vanilla extract, ground cinnamon, and a pinch of salt until smooth.

Gently fold the cooked rice into the custard mixture, ensuring the rice is evenly coated.

Pour the creamy rice mixture into the prepared baking dish, cover tightly with aluminum foil, and bake for 45 minutes. Remove foil and bake for an additional 15 minutes until golden and set.

Let the rice pudding rest for 15 minutes before serving. Enjoy warm or chilled.