Place the rice in a bowl, cover with hot water. Roughly crumble cinnamon stick into the rice and let it all sit and rest anywhere from 2 to 8 hours outside of the refrigerator.

Place half of the rice mixture in the blender with the coconut water and vanilla and blend until smooth. Strain into a pitcher or container. Place the other half of the rice mixture in the blender with the milk and the sugar, blend until smooth and strain into the same pitcher.

Stir well and serve over ice, or place in refrigerator until cold. Sprinkle ground cinnamon on top if desired.