Regardless of how healthy or nutrient-packed a smoothie is, it definitely has to taste good, and there are a variety of ways in which you could do this. To make it indulgent and sweet, you could add unsweetened cocoa powder which will make it taste like a chocolate milkshake if done right. If you'd prefer the taste of a classic shake, add a small amount of vanilla extract. For more earthy flavours you could incorporate spices such as cinnamon, ginger or nutmeg. Flax and chia seeds will also help complement earthy and aromatic tastes, and if paired with oats, it could also fill you up like a good breakfast.