Next, add all the ingredients to a high-powered blender: the frozen banana, lime zest, lime juice, vanilla yogurt, milk, spinach, and vanilla extract. Blend until smooth, adding more milk if needed to achieve your desired consistency. Taste the mixture and add sweetener if necessary; however, if you're using vanilla yogurt, it’s usually sweet enough on its own! Pour the smoothie into the prepared glass, then top with whipped cream and a sprinkle of shredded toasted coconut. This recipe serves 1, but feel free to double it to serve 2.