Combine 1 1/2 cups of uncooked white rice, 3 broken cinnamon sticks and 6 cups of hot water in a large glass jar
Cover and chill the mixture overnight
Remove a few of the large portions of cinnamon sticks and transfer the rice and liquid into a blender (blend in two batches, if needed)
Blend until the rice and cinnamon sticks are very fine
Place a fine mesh sifter or cheesecloth over a large jar and pour the rice mixture through the mesh
In a small saucepan, warm 4 cups of water over medium high heat
Add 12 ounces of evaporated milk, 14 ounces of sweetened condensed milk, 2 teaspoons of vanilla extract and whisk until smooth
Combine the strained rice milk with the warm milk mixture and add 2 cups of unsweetened almond milk
Chill the horchata in a covered jar for several hours before serving
Serve over ice