Halve the avocado, remove the pit and scoop the flesh from the skin. Peel the half banana and break it into a few large pieces. Gather the handful of spinach and lay out the dry ingredients—the flaxseed, spirulina and vanilla protein powder—ready for use.
Add the prepared avocado, banana and spinach to the blender jar. Add the flaxseed, spirulina and protein powder to the other ingredients. Then pour the unsweetened almond milk into the blender and add the ice cubes to chill everything well.
Turn the blender on to a low setting and gradually increase the speed. Let the machine run for about sixty seconds until the blades have completely pulverized all hard elements, such as the flaxseed and ice cubes. Check the consistency in the jar to see if the mixture is completely smooth and creamy.
Pour the smoothie from the blender jar directly into a tall glass. Drink the smoothie immediately to prevent the solid ingredients from separating and settling to the bottom.