Preheat oven to 350 degrees and line a 9×9 pan with parchment paper allowing it to hang over the edges for easy removal. You can also grease the pan really well but parchment paper makes is 100x easier.
Combine cookie crumbs and butter and stir until completely combined. Press into the bottom of the prepared pan.
Mix sweetened condensed milk and cocoa powder and pour evenly over cookie crumbs. Top with semi-sweet and dark chocolate chips and M&Ms.
Bake 25 minutes. Let cool completely and cut into squares. Seriously, they need to sit for at least an hour to solidify so they are easier to cut and serve. Enjoy.