Preheat the oven to 350°F (175°C) and line two baking sheets with parchment paper.

Pulse half of the pistachios in a food processor until finely ground.

In a bowl, whisk together the flour, baking powder, baking soda, and salt.

Cream the butter, light brown sugar, and granulated sugar until light and fluffy.

Mix in the egg yolks and vanilla extract until combined.

Fold in the finely ground pistachios until just incorporated.

Gradually mix in the dry ingredients until just combined.

Fold in the chopped dark chocolate and remaining chopped pistachios.

Scoop about 2 tablespoons of dough onto the prepared baking sheets, spacing them 2 inches apart.

Bake for 10-12 minutes, watching for a golden brown color.

Cool the cookies on the baking sheet for 5 minutes before transferring to a wire rack.

Sprinkle with flaky sea salt and garnish with additional pistachios and chocolate if desired.