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

In a stand mixer fitted with a paddle attachment, cream the softened butter, brown sugar, and granulated sugar on medium-high speed for 3-4 minutes until light and fluffy.

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

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

Reduce the mixer speed to low and gradually add the dry ingredients to the wet ingredients, mixing until just combined to avoid overworking the gluten.

Fold in 1.5 cups of the semi-sweet chocolate chips by hand.

Divide the dough into 12 equal portions (approximately 1/3 cup or 3.5 ounces each) and roll into smooth balls.

Place the dough balls on the prepared baking sheets, spacing them at least 3 inches apart.

Press the remaining 0.5 cups of chocolate chips into the tops of the dough balls for aesthetic presentation.

Bake for 10-12 minutes. The cookies should look set on the edges but slightly underbaked in the center.

Allow the cookies to cool on the baking sheet for at least 15 minutes to firm up before transferring to a wire rack.