The sweetness in this shake is coming from the banana, so the riper your banana is, the sweeter your shake will be. To freeze your banana, peel the banana and cut it into inch-wide slices and put into a plastic freezer bag. (Cutting it into slices first will help the frozen banana blend easier.) Place the bag into the freezer for several hours until the banana slices are fully frozen. Add the frozen banana to the rest of the ingredients in a blender and blend until smooth. If your blender needs more liquid to handle the frozen banana, you can add more of the almond milk or a dash of water.