Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.

In a large mixing bowl, cream together softened unsalted butter, granulated sugar, and dark brown sugar until light and fluffy (about 2-3 minutes).

Add a large egg and vanilla extract to the creamed mixture, beating well until fully combined (1-2 minutes).

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

Gradually incorporate the dry ingredients into the wet mixture until just combined.

Gently fold in chopped dark chocolate and optional pecans.

Cover the dough and chill in the refrigerator for 20-30 minutes.

Scoop the dough onto lined baking sheets, spacing them 2 inches apart. Sprinkle a pinch of flaky sea salt on top if desired.

Bake for 10-12 minutes, until edges are golden brown and centers are soft.

Allow cookies to cool on the baking sheet for about 5 minutes before transferring to a wire rack to cool completely.