Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a large mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until smooth and fluffy, about 3-5 minutes.

Add the egg and vanilla extract to the mixture and blend on low speed until well combined.

Gradually add the flour, baking soda, cocoa powder, and salt, mixing gently until just combined to form a thick dough.

Fold in the chocolate chips, ensuring even distribution throughout the dough.

Scoop equal-sized balls of dough onto the prepared baking sheet, spacing them about 2 inches apart. Gently flatten and add more chocolate chips on top if desired.

Bake in the preheated oven for 10 minutes, until edges are set but centers remain soft.

Cool cookies on the baking sheet for 10 minutes before transferring to a cooling rack.