Brew 120ml espresso and cool it completely before blending. For faster cooling, pour it into a shallow container and refrigerate for about 10 minutes. Do not blend hot or warm espresso with the smoothie — it melts the ice and frozen banana immediately, producing a thin drink instead of the thick texture this recipe is built around. That melting happens almost instantly on contact, since warm liquid transfers heat into frozen banana and ice far faster than the blending process itself can compensate for.

Melt the dark chocolate gently with the milk or cream until smooth and fluid, then allow it to cool until just slightly warm but still pourable. Drizzle thin irregular lines around the inside walls of four chilled glasses, then place the glasses in the refrigerator while making the smoothie. The chocolate must not be hot when it touches the cold glass or smoothie — warm chocolate becomes runny and disappears into the drink instead of leaving visible dark ribbons. That cold glass is doing real work here, setting the chocolate almost on contact so the drizzle holds its shape as a distinct ribbon rather than sliding down into a pool at the bottom.

Add to the blender in this order: cold milk, chilled espresso, Greek yogurt, protein powder, cocoa powder, vanilla, salt, banana, and ice. Add maple syrup or honey only if needed. Liquids go underneath the powders — this prevents dry cocoa and protein powder from forming pockets around the blades or sticking heavily to the blender walls. That order matters more here than in most smoothies, since two separate dry powders are involved, and either one left sitting above the liquid line tends to cake against the sides rather than disperse evenly through the blend.

Blend on low briefly to combine, then increase to high and blend for about 30–45 seconds until completely smooth. Stop and scrape down the blender if any protein or cocoa remains stuck to the sides, then blend another 10–15 seconds if needed. The smoothie should be thick, glossy, and homogeneous, with a soft aerated surface but not a large foam cap. That brief scrape-down step matters specifically because protein and cocoa powder are the two ingredients most likely to resist full incorporation, clinging to the walls even after the rest of the mixture has gone fully smooth.

Check before serving: if it's too thick, add cold milk 15–20ml at a time; if it's too thin, add additional frozen banana or a small handful of ice; if the coffee flavour is weak, add another 30ml chilled espresso rather than instant coffee powder. Protein powder continues absorbing moisture after blending, so stop slightly looser than the absolute final target if the smoothies will sit for several minutes before serving. That continued absorption is exactly why a smoothie that looked perfectly thick straight off the blades can turn noticeably denser by the time it's actually poured and served.

Pour immediately into the prepared glasses, approximately 250ml per serving. Dust very lightly with cocoa powder and scatter dark chocolate shavings over the center, then serve immediately. That immediate serving protects both the chocolate drizzle's crisp ribbon and the smoothie's own thickness, since the glass's cold advantage over the drizzle and the ice's advantage over the protein powder both fade the longer the finished drink sits before reaching the table.