Preheat the oven to 350 degrees F. Line two baking sheets with parchment paper.
In a large bowl, cream the butter and sugars together for about 2-3 minutes.
Add the egg and vanilla. Beat for another minute or 2.
Add the flour, cocoa powder, baking soda, and salt, mixing until combined. The dough will be soft, but you do not need to chill it.
Use a small cookie scoop to scoop the dough into balls. Roll them in the palms of your hands to make round spheres. Then roll them in a shallow bowl of sugar.
Place the balls of dough on the prepared baking sheets and bake for 7-9 minutes. Mine were cooked at 9 minutes exactly.
Let them cool for about 4 minutes before pressing the peppermint kiss into the cookie.
