First, add milk and the frozen banana to the blender and blend until smooth. If you are using fresh banana (not frozen), add ice cubes to the blend.
Once you have your desired consistency* (and never before!), add the chocolate and pulse a few times until just combined. You don’t want to over-blend or the chocolate will get too small.
If you want, you can decorate with some chocolate or cream on top.
Notes
If your smoothie isn’t thick enough, add a few ice cubes or another frozen banana to it. Adding a tablespoon of peanut butter or whey protein powder also makes it creamier.
If you find the smoothie too thick, add more milk until it reaches your desired consistency.