Preheat oven to 350°F (180°C).

Spread pistachios in one layer on a baking tray lined with parchment paper. Toast pistachios in preheated oven for 6-8 mins.

Remove from oven and let cool on tray. (optional: rub pistachios in between a clean towel to remove skins)

Combine sugar, brown sugar, salt, and melted butter in a mixing bowl. Mix until no lumps remain.

Add the egg and vanilla and mix until batter is smooth and flows off spatula like molten lava.

With a large sieve, sift flour and baking soda into batter. Fold into mixture until just combined. Do not overmix!

Gently fold in chocolate and pistachios, reserving a small handful of both for later (optional).

Cover mixing bowl with plastic wrap and let sit in the fridge for about 30 mins or overnight.

With an ice cream scoop or large spoon, scoop out 1-2 inch spherical mounds of the chilled cookie dough onto a baking tray lined with parchment paper. Leave at least 3-4 inches between adjacent cookies and sides of the tray for spreading (about 6 cookies per large tray).

With the extra pieces of chocolate and pistachios you set aside earlier, press a few pieces of both on top of each cookie dough mound (optional: skip this step if you don't care about "seeing" the chocolate and pistachios on the tops of your cookies)

Let cool completely on baking tray before handling.