Place the rice in a fine strainer or sieve and rinse very well under cold water to remove the starch and any dust.

In a medium to large saucepan over high heat, stir together the water, rice, 1-1/2 cups of milk, and the cinnamon stick. Bring this to a boil. Then, reduce the heat to low and cover the pot. Cook for 20 minutes until the rice is tender and the liquid is absorbed.

Increase the heat to medium-high. Stir in the remaining milk, evaporated milk, sugar, and vanilla. As soon as the mixture comes to a boil, cook for 5 minutes stirring often.

Ladle the rice mixture into a blender and puree until smooth and creamy. You will likely have to do this in batches.

Pour the atole into coffee mugs or heat-proof glass Irish coffee mugs. Sprinkle some cocoa powder on top of each drink. Serve while warm.