Brown butter in a medium saucepan over medium-low heat stirring constantly with a wooden spoon for approximately 7 minutes or until the butter gets foamy and releases a nutty aroma.
Once browned bits begin to form on the bottom of the pan, remove from the heat and set aside until cooled.
Whisk together flour, baking soda and salt in a medium-sized bowl. Set aside.
In a separate bowl, beat browned butter, brown sugar and granulated sugar with an electric mixer until light and creamy — approximately 1 minute.
Add the vanilla and eggs, one at a time, beating after each addition until incorporated.
Reduce mixer speed to low then add dry ingredients to wet, mixing until almost combined and flour is still visible.
Reserve 1/4 cup of chocolate chunks and 1/4 cup of chopped pistachios for later use.
Add the balance of chopped chocolate and chopped pistachios to the cookie batter then stir with a spoon until evenly distributed. Avoid overmixing.
Using a large, 2 1/2 Tablespoon-sized cookie scoop, scoop cookies onto parchment lined baking sheets, spacing cookie balls 2 inches apart.
Top each cookie ball with the reserved chocolate chunks and chopped pistachios.
Cover baking sheets with plastic wrap then chill in the refrigerator for a minimum of 4 hours or up to 2 days. (Mine chilled overnight.)
Preheat the oven to 350F.
Remove plastic wrap from baking sheets and bake for 10 to 12 minutes or until the cookie edges are set but the centers are still soft.
Remove cookies from oven and allow them to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.Note: Cookies may spread a bit as they bake. To reshape, place the rim of a large drinking glass over warm cookies while they are still on the baking sheet then gently swirl the glass in a circular motion until each cookie is symmetrically round. If desired, sprinkle each cookie with sea salt before serving.
Store cookies in an airtight container at room temperature up to 5 days.