Preheat the oven to 350° Fahrenheit. Line a large cookie sheet with parchment paper and set aside.
Add the dry brownie mix, all-purpose flour, eggs, and oil to a large bowl. Mix by hand or with a hand mixer until a thick dough forms.
Use a rubber spatula or wooden spoon to fold the mini chocolate chips and mini M&M’s into the batter.
Using a cookie scoop, place scoops of dough 2 inches apart on the prepared baking sheets.
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, I start to check the cookies around 7 minutes. If you bake for too much time, the cookies will be hard as a rock!
Remove the cookies from the oven and immediately place a few extra mini chocolate chips and mini M&M’s on top of the cookie.
Allow the cookies to cool on the baking sheet or a wire rack 10-15 minutes before removing to cool completely. The cookies should have crispy edges and a warm chewy center.