Preheat the oven to 350° Fahrenheit. Line baking sheets with parchment paper and set aside.
Add the dry brownie mix, all-purpose flour, eggs, peppermint extract and oil to a large bowl. Mix with an electric hand mixer or a stand mixer on low speed until the mixture mis well-combined. The batter will be thick.
Use a rubber spatula or wooden spoon to gently fold in the mini chocolate chips.
Using a cookie scoop, place scoops of dough 2 inches apart on the prepared pans.
Bake for 8-10 minutes or until the edges are set but the middle is still fudgy and slightly undercooked. Take care not to over-bake the cookies, they will continue to set and harden as they cool.
Remove the cookies from the oven and immediately place crushed peppermint on top of each cookie.
Allow the cookies to cool on the baking sheet for10-15 minutes before removing to a wire rack to cool completely