Fill a cocktail shaker with ice. Pour in the Kahlua, vodka, and espresso.
Cover and shake vigorously for 20-30 seconds.
Strain into a martini glass and garnish with a couple of espresso beans. Serve immediately.
Notes
If you don't have espresso available, a strong cold brew coffee concentrate would be a good substitute. You could also use instant espresso powder or very strong coffee.