Place rice in a strainer and rinse thoroughly with cool water, then transfer to a large bowl that will fit in your fridge.
Bring 6 cups of water almost to a boil, you want it very warm to soften the rice quicker, but not boiling, then pour on the rice. Drop in 2 cinnamon sticks and allow it to cool, then cover and place in the fridge for at least 4 hours or overnight.
In 2 batches blend half the rice mixtures, along with one cinnamon stick, on high speed in a blender for about 4 minutes. Strain very well with a fine mesh strainer or nut milk bag into a large pitcher and repeat with the remaining.
Pour sweetened condensed milk, evaporated milk and vanilla extract to the pitcher and stir well to dissolve and combine.
Serve immediately or chill until ready to use. Serve over ice with a sprinkle of cinnamon.
Notes
Blending Time: Blend the rice mixture thoroughly to release as much flavor and starch as possible; about 3-4 minutes.
Straining Well: Use a fine mesh strainer, cheesecloth or nut milk bag to remove all rice particles for a smooth drink.
Cinnamon Balance: If soaking overnight, taste before serving. Cinnamon can become stronger the longer it sits.
Stir Before Serving: Give the pitcher a good stir before pouring, since the rice mixture can naturally settle.
Storage: Store in a covered pitcher or airtight containers for up to 3-4 days. Stir well before serving.
Serve over Ice: Horchata is best served very cold over ice, which enhances the creamy texture and cinnamon flavor.
Makes: This recipe makes about 3 liters; serving is about 1 cup.