01 -
Pulse the pistachio kernels in a food processor until a relatively fine powder is obtained, avoiding overprocessing to prevent oil release.
02 -
Add flour, powdered sugar, and salt to the ground pistachios and pulse briefly to mix evenly.
03 -
Add the very cold cubed butter and pulse until small pea-sized crumbs form evenly throughout the dry mixture.
04 -
Mix in the egg yolk, vanilla extract, and optional lemon zest until a rough, slightly sticky dough forms, about 30 seconds to 1 minute.
05 -
Transfer dough between two large sheets of parchment paper and roll out to 1/4 inch (6 mm) thickness. Place on a baking tray and chill in the refrigerator for at least 1 hour.
06 -
Preheat the oven to 325°F (160°C) and line a baking sheet with parchment paper or a perforated baking mat.
07 -
Remove chilled dough from refrigerator, peel off parchment, and cut dough into shapes using a 2-inch (6 cm) fluted cookie cutter. Space cookies evenly on the prepared baking sheet.
08 -
Bake for 15 minutes or until edges turn slightly golden. Cool on a wire rack for at least 15 minutes before handling.
09 -
Melt chopped chocolate in a heatproof bowl over a double boiler or microwave. Drizzle melted chocolate over cooled cookies and sprinkle with chopped pistachios. Let chocolate set at room temperature or refrigerate for 15-20 minutes.