Cool your espresso first. Pull your shot and set it aside to cool completely — or spread it over an ice cube and discard the cube once it melts down. You want it room temp or colder before it goes in the shaker.

Combine all ingredients in a shaker. Add the vodka, espresso, coffee liqueur, pistachio syrup, and orange blossom water (if using) to your Boston shaker.

Add ice and shake hard. Fill the shaker with ice and shake vigorously for at least 15–20 seconds. This is what builds the foam — don't go easy on it.

Double strain into a chilled coupe. Use your shaker's built-in strainer plus a fine-mesh strainer set over the glass. Strain slowly and let the foam settle on top.

Garnish with pistachio dust. Pinch a small amount of finely crushed pistachios and dust over the top of the foam just before serving.

Serve immediately. The foam is best in the first two to three minutes.