Combine all ingredients except the ice in a high-speed blender and blend until perfectly smooth, scraping down the sides a few times if necessary. If you use fresh fruit, you may wish to add a few ice cubes to achieve a colder, thicker smoothie texture. Pour the smoothie into a large glass and garnish with a sprinkle more of cinnamon, if desired, or transfer to a thermal mug and take it on-the-go.