In a large mixing bowl, combine 1 cup of unsalted butter and ½ cup of powdered sugar. Use an electric mixer on medium speed, beating until light and fluffy, about 3-5 minutes.

Sift in 2 cups of all-purpose flour and gently mix until just combined. Fold in ½ cup of finely chopped pistachios.

Shape the dough into two logs, each about 1.5 inches in diameter. Wrap tightly in plastic wrap and refrigerate for at least 2 hours.

Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.

Remove the dough from the refrigerator and slice each log into ¼-inch rounds. Place the slices on the prepared baking sheets.

Bake for 10-12 minutes until the edges are lightly golden. Let cool on baking sheets for 5 minutes, then transfer to a wire rack.