Chop the pistachios finely with a sharp knife, or add them to a food processor and pulse. You don't want a sandy texture, but you want a mix of sizes, mostly small pieces that will mix evenly in the dough. 1 cup Finely Chopped Pistachios
Add the butter, powdered sugar, and vanilla to a large bowl or stand mixer and beat it for 1 to 2 minutes, until its smooth and creamy. 1 cup Unsalted Butter, 1/2 cup Powdered Sugar, 1 tsp Vanilla Extract
Add in the flour, and salt and mix it into the butter mixture until just combined. 2 1/4 cups All Purpose Flour, 1/2 tsp Salt
Add in the pistachio pieces and gently mix them into the dough until evenly distributed.
Scoop the dough into 1 TBS portions (about 20g of dough each) and roll them into balls, about 1 inch in size. Place them on a lined baking sheet and place the sheet in the fridge to chill for 30 minutes to 1 hour.
Preheat the oven to 350 F. Line a baking sheet with parchment paper or a silicone liner, and place the cookies on the sheet 1 inch apart.
Bake the cookies for 9 to 11 minutes, or until the bottom of the cookies are light brown, and the tops are set.
Cool for about 5 minutes on the cookie sheet, then transfer them to a wire cooling rack to cool completely.