Prep the coffee. Brew your coffee ahead of time and let it cool, or use instant coffee dissolved in a small amount of cold water. Cool coffee blends better and keeps the smoothie thick.
Load the blender. Add milk, coffee, cocoa powder, banana, and a pinch of salt. If using add-ins like nut butter or protein powder, add them now.
Sweeten to taste. Add a small amount of maple syrup or honey.
Start with 1 teaspoon; you can always add more later.
Blend until smooth. Start on low, then increase to high for 30–45 seconds. If it’s too thick, splash in more milk. If it’s too thin, add a few ice cubes or more frozen banana.
Taste and adjust. Add more sweetener, cocoa for deeper chocolate, or another splash of coffee for a stronger coffee note.
Re-blend for a few seconds.
Serve immediately. Pour into a chilled glass. For a little flair, dust the top with cocoa powder or cinnamon.