In a medium pot, bring rice, water, and salt to a boil. Lower heat and maintain a good simmer, uncovered, until the rice absorbs the water, stirring regularly so the rice doesn’t stick.
Add the milk, sugar, vanilla seeds and pod, and cinnamon stick, and stir in. Continue to simmer, covered, and stirring regularly, until the milk is absorbed and rice is tender, about a half an hour or so, checking regularly and adding more milk as needed.
Remove vanilla pod and cinnamon stick. Taste and add additional sugar if desired. Transfer porridge to a serving dish or to four bowls, tucking a single whole almond somewhere inside one of the servings. Sprinkle with additional sugar and ground cinnamon and top with a pat of cold butter.