Add the frozen banana chunks, hulled strawberries, and liquid (start with ¼ cup and adjust according to desired consistency) into a blender.
Sprinkle cinnamon to taste over the ingredients in the blender.
If using fresh bananas, add 1-2 ice cubes for a colder smoothie.
Optional: Add additional spices such as nutmeg, cloves, ginger, or vanilla for extra flavor.
Blend the ingredients in spurts until smooth, pausing occasionally to scrape down the sides of the blender if needed.
Once the desired consistency is reached, pour the smoothie into glasses and serve immediately.