Measure out cereal and place in a large bowl.
In a small, microwave safe bowl, melt your chocolate chips and Biscoff. (I start out with 30 seconds, stir, then heat in 15 second increments until melted.)
Pour melted chocolate mixture over the cereal. Stir gently to coat.
Add 3/4 cup brownie mix to a large ziploc bag, dump chocolate coated cereal into ziploc, and shake to coat.
Spread brownie coated mixture on a large baking sheet to completely dry.
Once cereal mix is dry (which only takes a few minutes), you can add anything you like to it (I used mini marshmallows and M&M's - but during the holidays, themed candies are fun to add) or you can leave the mix plain - b/c it is delicious all by itself!