Place the white rice, walnut halves, and ground cinnamon in a food processor or blender. Pulse the food processor until the walnuts have broken into small pieces and the rice has broken into smaller pieces.

Pour the ground walnuts and rice into a large pitcher and add the cinnamon stick and enough water to fill the pitcher. Stir well and cover. Let it soak for at least 8 hours or overnight.

After it’s soaked, strain out the excess liquid and reserve both the liquid and the rice and walnuts separately.  Discard the cinnamon stick.

Pour the rice and walnuts back into a food processor or blender and pour in the milk. Blend it well until it is as smooth as it can get.

Strain the milk through a fine sieve into the left over rice milk from the first straining and discard any rice or walnut bits that are left.

Add the vanilla and sugar to the rice milk and stir well to combine.

Pour the Horchata into glasses and sprinkle each with a pinch of cinnamon and cocoa and add a mint leaf to each. Serve immediately or refrigerate until ready to use.