In a medium pot, add rice, 2 cups of milk, and salt.
Bring to a gentle boil over medium heat, stirring occasionally.
Reduce heat and simmer until the milk is mostly absorbed and the rice is soft (about 15–20 minutes).
Stir in the remaining 2 cups of milk, sugar, vanilla essence, and butter.
Cook over low heat for another 15–20 minutes, stirring often, until thick and creamy.
Serve warm or chilled. Sprinkle cinnamon on top if desired.