Preheat the oven to 350°F. Line two baking sheets with parchment or use a silicone baking mat.

In a medium bowl, beat together the butter and sugars.

Add the egg, beating well and scraping the bottom and sides of the bowl.

Add the vanilla and peppermint, beating to combine.

Add the flour, cocoa, baking soda, and salt, beating to combine.

Stir in the chocolate chips.

Using a teaspoons cookie scoop, drop cookie dough onto the prepared baking sheets, spacing them about 1 1/2" to 2" apart.

Bake the cookies for 12 to 13 minutes.

Remove them from the oven, and transfer them to a rack to cool. .