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

In a large mixing bowl, cream together softened butter, granulated sugar, and brown sugar until light and fluffy.

Add eggs one at a time, beating well after each addition, then stir in vanilla extract.

In a separate medium bowl, sift together all-purpose flour, cocoa powder, baking soda, and salt.

Gradually incorporate the dry ingredients into the wet mixture until just combined, taking care not to overmix.

Fold in the semi-sweet chocolate chips using a spatula.

Drop rounded tablespoons of dough onto the prepared baking sheets, spaced approximately 2 inches apart.

Bake for 9 to 11 minutes until the edges are set but the centers still appear slightly soft.

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