In a blender, blend together the banana, ice cubes, blueberries, and liquid (water or milk substitute) until smooth.
Add spinach and blend again until completely smooth and creamy.
No sweetener is needed in this recipe, as the blueberries carry the flavor and are plenty sweet on their own, but if you find this smoothie a bit too bland, try adding a touch of agave nectar to give it a bit more zing. Blend to incorporate.
