Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.
In a large bowl, cream together the unsalted butter and brown sugar until smooth and creamy.
Add the egg and vanilla extract to the butter-sugar mixture. Beat until well combined.
Sift the cocoa powder, all-purpose flour, baking soda, and salt into the wet ingredients. Mix until just combined.
Fold in the chocolate chips until evenly distributed throughout the dough.
Shape the dough into tablespoon-sized balls and place them on the prepared baking sheets, leaving enough space between each for spreading.
Bake for 8-10 minutes or until the edges are set but the centers are still slightly soft.
Remove the cookies from the oven and immediately press a milk chocolate kiss into the center of each cookie.
Allow the cookies to cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely.
