Chewy Chocolate Mint Cookies

Preheat the oven to 350 degrees. In a medium bowl, combine flour, cocoa powder, baking soda, and salt. Set aside.
In a separate bowl or the bowl of a stand mixer, cream the butter, brown sugar, and white sugar on medium-high until fully combined and slightly fluffy, about a minute. Add the eggs + egg yolks one at a time, beating well after each addition to combine. Add the vanilla; blend well.
Carefully pour the flour mixture into the butter+sugar mixture and mix on low until combined. Pour in the chocolate peppermint bits** and beat on medium until incorporated. **Note: I used Trader Joe's Peppermint Bark Baking Bits; if you can't find them, you could add chocolate mint chips or a combination of chocolate chips and candy cane bits. If you use candy cane bits be sure to spray your cookie sheet with cooking spray, as they will stick!
Roll 2-tablespoon balls of dough and drop onto a cookie sheet. Bake for 8-10 minutes, or until the edges just look done - you want them to be a little gooey-chewy in the middle! Cool completely on a wire rack.