Place your pistachios into a food processor and lightly pulse until finely ground, or chop finely by hand.
Place in a small bowl. Add flour and salt. If using lightly salted, just a pinch of sea salt is necessary. If using unsalted, up to about ¼ tsp. Mix together and set aside.
Preheat oven to 350°F. Line two baking sheets with parchment and have a third sheet of parchment or silpat out.
Make sure your sugar and cream are measured out. Add your vanilla to your heavy cream.
Brown the butter. Place your butter in a stainless or light colored sauce pan over medium heat. As the butter melts, stir with a rubber spatula. The butter will bubble loudly, then subside. It will begin to foam. When the butter is fragrant and and the milk solids have been toasted to a medium golden brown, immediately reduce heat to low and add brown sugar, cream and vanilla.
Stir continuously for 1-2 minutes until the sugars have melted and your have a caramel like consistency.
Pour your wet ingredients into a medium-large bowl. Add your flour, pistachios and salt and mix together until they form a sort of paste.
Using a 1 tsp to 1.5 tsp (max) scoop all of your cookies out onto your third sheet of parchment or silpat.
Depending on the size of your tray, add 5-6 cookies to one of your parchment lined baking sheet leaving 3-5 inches surrounding each cookies to allow for spreading.
Bake your cookies on the center rack for 7-8 minutes. The cookies are done when the edges are lightly browning and the cookies are bubbling. Remove from the oven and leave on the baking sheet for about 5 minutes.
Fill your second baking sheet with cookies and repeat.
When the cookies have firmed up a little, carefully transfer them to a wire cooling rack to continue to cool. I find it easiest to pull the parchment away from the cookie to slide the spatula underneath for transferring to create the least amount of cookie breakage.
Allow the cookies to fully cool. Cookies can be stored with wax paper or parchment between layers. They additionally can be drizzled with white, milk or dark chocolate. Enjoy!
