Why This Works
An espresso martini is really a coffee sour: bitter espresso, a little sweetness, and a rich texture from a hard shake. Take the alcohol out and nothing essential is lost, because the drink was always carried by the coffee, not the vodka.
The signature crema, that pale foam on top, is pure technique. Coffee is full of natural oils and soluble compounds that emulsify when you shake them hard with ice, whipping air into a stable foam. Shake longer and harder than feels necessary, then double-strain so the foam sits clean on top.
Use real espresso or a strong cold brew, and make sure it is cold before it hits the shaker. Warm coffee melts the ice too fast and flattens the foam, leaving you with a thin, watery drink instead of a silky one.
The Alcohol-Free Swap
A good alcohol-free coffee liqueur adds the roasted sweetness and body a classic espresso martini gets from coffee liqueur like Kahlua. No bottle on hand? Use an extra ounce of cold brew and a little more rich simple syrup.