Brew your espresso and allow it to cool to room temperature, or use cold brew concentrate straight from the refrigerator. Hot espresso will melt the ice and create a watery drink.
Fill a cocktail shaker with ice cubes until it's about three-quarters full.
Pour the vodka, coffee liqueur, cooled espresso, and simple syrup into the shaker.
Seal the shaker tightly and shake vigorously for 15-20 seconds until the outside of the shaker becomes frosty and you hear the ice breaking down.
Strain the mixture into chilled martini glasses, making sure to capture that beautiful foam layer on top.
Garnish each glass with three coffee beans floating on the foam and serve immediately.