To a blender, add the rice and 2 cups of hot water. Blend until the rice is pulverized, then add the remaining hot water and 2 cinnamon sticks.
Transfer the rice mixture to the fridge and let it sit for 2-3 hours. Blend again until it is smooth.
Pour the rice mixture through a triple layer of cheesecloth and a fine-meshed sieve. This step can take a long time so I like to pull up the sides of the cheesecloth into a pouch and gently squeeze out the liquid.
Stir in the evaporated milk, condensed milk*, instant coffee (dissolved in 1 cup of hot water), and 2 cups of cold water. Chill until ready to serve then pour over lots of ice. Enjoy!
Notes
I personally do not like my horchata to be too sweet, so I only add 1 can of sweetened condensed milk. If you like it sweeter, you can easily add more. If you want it to taste as sweet as the restaurants, I'd add up to another ½ can.