Prepare the Pistachio Crumbs:
Pulse the pistachios in a food processor until they form small crumbs. You’ll need ¾ cup of very finely chopped pistachios for the cookie dough. Set aside.
Make the Cookie Dough:
Using a handheld or stand mixer fitted with a paddle attachment, beat the softened butter for 1 minute on medium speed until smooth and creamy.
Add the confectioners’ sugar, vanilla extract, and almond extract, then beat on medium-high speed until combined.
Gradually add the flour, ¾ cup pistachio crumbs, and optional food coloring. Beat on medium-high speed until fully incorporated. The dough will be thick but should come together after mixing.
Chill the Dough:
Cover the cookie dough tightly and chill it in the refrigerator for 30 minutes, or up to 3 days. If chilling for more than 2 hours, let the dough sit at room temperature for about 30 minutes before rolling into balls, as it will be quite stiff after extended chilling.
Bake the Cookies:
Preheat your oven to 350°F (177°C). Line large baking sheets with parchment paper or silicone baking mats.
Roll the cookie dough into balls, about 1 tablespoon of dough each, and place them 2 inches apart on the prepared baking sheets.
If the dough feels crumbly, keep rolling it between your hands to warm it up and bring it together.
Bake the cookies for 14-15 minutes, or until the bottom edges are lightly browned and the tops are just barely browned.
Allow the cookies to cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.
Make the Brown Butter Icing (Optional):
Slice the butter into pieces and melt it in a light-colored skillet over medium heat. Stir occasionally.
After 5-6 minutes, the butter will begin to brown, forming lightly browned specks and giving off a nutty aroma.
Remove from heat and let the browned butter cool for 5 minutes. Whisk in the confectioners’ sugar, milk (or cream), and vanilla extract until smooth. Adjust the thickness of the icing by adding more confectioners’ sugar or milk if needed.
Decorate the Cookies:
Dip the cooled cookies into the brown butter icing or drizzle it over the top. If lightly coated, the icing will set after 1-2 hours.
Store iced cookies in an airtight container at room temperature for 1 day or in the refrigerator for up to 1 week. Cookies without icing can be stored at room temperature for up to 1 week.