Preheat oven to 350 degrees F (180 C). Line baking sheets with parchment paper or silicone liners; set aside.

In a medium bowl, whisk together flour, cocoa, baking soda, and 1/2 teaspoon sea salt. Set aside.

With a stand or hand mixer, cream together the butter and sugars for 2-3 minutes. Add in eggs, one at a time, followed by the vanilla. Scrape down the sides of the bowl and mix until well-combined.

Add flour mixture and beat on low speed just until incorporated. Stir in the chocolate chips and pistachios by hand.

Scoop the dough into heaping tablespoons and place on prepared baking sheet, about 2 inches apart. (You can either leave the scoops as they are, or roll them slightly with your hands into smooth balls. See photos above for a visual of what each will look like when baked.) Sprinkle the top of each cookie with additional sea salt.

Bake cookies for 9-10 minutes, until just set but still soft in the center. Do not over-bake. Remove from oven and let sit on baking sheet for 5-10 minutes, then move to a wire cooling rack. Cookies will keep well stored at room temperature for 2-3 days.