Instead of messing with the wiring, [Marco] took the non-invasive approach and is using a DIY coil to detect the magnetic field of the espresso machine’s pump and start a shot timer. An LM358 ...
Pour the shot of espresso over the ice, then pour in the milk if making an iced latte, adding more or less to taste. Stir in the condensed milk to sweeten, if using. Serve immediately. If you want ...