Make Pistachio Paste by blending roasted salted pistachios and olive oil until smooth.

Prepare the cookie dough by creaming softened butter, light brown sugar, and granulated sugar together.

Combine dry ingredients in a separate bowl and gradually add to the wet mixture, stirring until mixed.

Fold in dark chocolate chunks into the dough until evenly distributed.

Chill the dough in the refrigerator for 2 hours to retain shape while baking.

Preheat the oven to 350°F (175°C) and prepare baking sheets. Scoop balls of dough onto sheets, sprinkle reserved pistachios, and bake for 10-12 minutes.

Cool cookies on the baking sheets for 5 minutes before transferring to a wire rack and adding flaky salt, if desired.