Chop Pistachios: Add half of the pistachios (1/3 cup) to a food processor and pulse into fine crumbs. Set aside. Pulse remaining 1/3 cup just a few times, to chop them. Set aside.

Melt butter just until barely melted. Set aside to cool to room temperature.

Dry Ingredients: Combine flour, baking soda and salt in a small bowl and set aside.

Wet Ingredient: Mix melted butter and both sugars until well combined. Add egg, egg yolk, and vanilla and stir until combined. Stir in pistachio crumbs.

Combine: Add dry ingredients and stir to combine. Stir in most of the pistachios pieces and chocolate--I like to reserve some for topping on the baked cookies hot out of the oven.

Chill: The dough will be soft. Refrigerate it for at least 30 minutes or up to 2 days (or freeze for longer).

Bake: Heat oven to 350 degrees F. Line a baking sheet with parchment paper or a silpat baking mat. Divide dough into 18 balls (about 60 grams each) and place on a cookie sheet 2 inches apart. Bake for 10-14 minutes or until set on top.

Garnish: Immediately out of the oven add a few chocolate pieces in each, sprinkle with pistachio, and a tiny pinch of flake salt.

Cool for 10-15 minutes on the baking sheet before moving to a wire cooling rack.