In a food processor, combine 1 cup confectioners’ sugar, ⅔ cup chopped shelled pistachios, and pistachio pudding mix. Process until the pistachios are finely ground, 15-20 seconds.

In a separate bowl, add the butter and beat until creamy with a mixer, approximately 1 minute on a medium-low speed. Add the ground pistachio mixture and beat until well blended, approximately 1 minute on a medium-low speed.

Add in 2 teaspoons vanilla extract and the flour mixture, beating just until combined. The resulting dough should be crumbly in appearance, like pebbles.

Pour the dough onto a large piece of plastic wrap and form into a ball, making sure it’s covered on all sides. Chill until firm, around 2-3 hours, but up to 24 hours in advance.

When the dough has chilled and firmed up, remove it from the refrigerator and let sit at room temperature until it softens up a bit, around 45 minutes.

Preheat the oven to 350°F. Using a cookie scoop, scoop the dough into even sizes. Optional: roll each piece between your palms to form a ball. I leave mine with a flat bottom.

Very lightly spray a baking sheet with cooking spray. Arrange the balls 1-1 ½ inches apart on baking sheets - they don't need a lot of room because they don’t spread out as they bake.

Bake until the edges of the cookies barely begin to brown, 12 to 14 minutes.

Let the cookies cool on the baking sheets for around 5-7 minutes.

Make the powdered sugar coating. Add ¼ cup confectioners’ sugar and ¼ cup pistachios to the food processor. Process until the pistachios are finely ground and powdery. Set aside.

Roll each cookie in the confectioners’ sugar and pistachio mixture while still slightly warm. Repeat until all the cookies are coated.