01 - Preheat the oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together the flour, cocoa powder, baking soda, and salt until evenly blended.
03 - Using an electric mixer or whisk, beat the softened butter with granulated sugar and brown sugar until creamy and light, approximately 2 minutes.
04 - Add the egg and vanilla extract to the creamed butter mixture, mixing until fully incorporated.
05 - Gradually add the dry ingredient mixture to the wet ingredients, stirring gently until just combined. Avoid overmixing.
06 - Carefully fold in the semi-sweet chocolate chips until evenly distributed throughout the dough.
07 - Using a tablespoon, scoop dough onto the prepared baking sheets, spacing portions about 2 inches apart to allow expansion.
08 - Bake in the preheated oven for 11 to 12 minutes, until edges are set and centers appear slightly underbaked.
09 - Allow cookies to cool on baking sheets for 5 minutes before transferring to a wire rack to cool completely.