Prep the banana. Peel and slice a ripe banana, then freeze the slices in a single layer. This gives your smoothie a creamy, milkshake-like texture.
Add liquids to the blender first. Pour in 1 cup of your chosen milk.
Liquids at the bottom help the blades blend smoothly and prevent air pockets.
Layer in the solids. Add the frozen banana, cocoa powder, nut or seed butter, spinach, vanilla extract, and a pinch of salt. If using protein powder, add it now.
Adjust sweetness. If your banana isn’t super ripe or you prefer a sweeter smoothie, add 1 pitted date or 1–2 teaspoons of honey or maple syrup.
Blend until smooth. Start on low speed, then increase to high for 30–60 seconds. If it’s too thick, add a splash more milk.
If it’s too thin, add a few ice cubes and blend again.
Taste and fine-tune. Add an extra teaspoon of cocoa for deeper chocolate flavor, or another pinch of salt to sharpen the taste. Blend briefly to combine.
Serve right away. Pour into a chilled glass. For a fun finish, top with cacao nibs, a sprinkle of cinnamon, or a few chia seeds.