Step 1: Bring water, butter and salt, to a boil in a medium saucepan.
Step 2: Add the rice, return to a boil, then reduce heat to the lowest setting. Stir occasionally and cook until rice has absorbed the water but it still al dente, 15 to 20 minutes.
Step 3: In a separate saucepan bring milk, vanilla, sugar, and cinnamon to a simmer. Add the cooked rice and cook over medium-low heat until rice absorbs most of the milk and mixture starts to get thick and silky, 10 to 15 minutes.
Step 4: Refrigerate until cool and set.