Preheat the oven to 350 degrees F. Line two baking trays with parchment paper and set aside.
In a large bowl, beat the butter and sugars together until the mixture is smooth and fluffy, about 2-3 minutes. Next, add the eggs, vanilla and peppermint extract and beat until combined and smooth.
Sift the flour, cocoa powder, baking soda, and salt on top of the wet mixture and mix everything together to just combine the dough. Near the end of mixing, fold in the chocolate chips.
Use a tablespoon to drop out heaps of dough (slightly larger than a golf ball) onto the parchment lined baking sheets. Bake in the oven for 10-12 minutes, until the bottoms are firm and the tops are puffed up.
While to cookies are still hot, nestle the peppermint candy/candy cane pieces into the cookies. You have to do this while the cookies are still hot so that you can easily insert the candy. If you wait for them to cool, it's much more difficult to insert the candy and you might break the cookie.
Let the cookies cool for 5-10 minutes and then eat! I love serving these cookies just slightly warm with a glass of milk.