Banana: A banana that has some green left or is still quite yellow won't work as well. Just like with banana bread, an over-ripe banana is the best choice to add the right sweetness for this smoothie.
Frozen bananas also work great in this recipe! If you're like us, we always keep over-ripe bananas in the freezer, ready for recipes like this one. If using a frozen banana, your smoothie may be slightly thicker.