Preheat your oven to 175 degrees Celsius
In your stand mixer, with the paddle attachment, beat together butter and sugar on medium speed until creamed together.
Add in the two eggs, one at a time, and allow them to mix in fully.
Add in your peppermint extract.
Combine your flour, cocoa powder, baking soda and salt in bowl.
Add your dry ingredients to the mixer, slowly, combining them all. You will need to scrape down the bowl to ensure it all combines.
On a parchment lined baking tray, scoop out blobs of the cookie dough, evenly spacing them out.
Bake for 9 minutes, until the edges are crispy and the top looks no longer wet.
Allow cookies to cool. If you'd like to decorate, melt your white chocolate and add to a piping bag.
Pipe stripes to one side of the cookie and add on the sprinkles.