01 - Place banana, milk, peanut butter, cocoa powder, honey or maple syrup (if using), vanilla extract (if using), and ice cubes (if using) into a blender.
02 - Blend on high speed for 30 to 45 seconds until mixture is creamy and smooth.
03 - Taste the smoothie and add additional sweetener if desired, then blend briefly to combine.
04 - Divide the smoothie evenly between two glasses and serve immediately.