2. Prepare brownies according to box and stir in 1/2 cup of semi-sweet chocolate chips. Bake brownies according to package directions. Remove from oven.
3. Sprinkle marshmallows on hot brownies. Return to oven. Bake for 3 minutes.
4. Place chocolate chips and peanut butter in medium saucepan. Cook on low heat. Stir constantly until chips are melted. Add rice cereal. Mix well. Spread mixture over marshmallow layer. Refrigerate until chilled.
*Tip: Make sure the marshmallow layer is a bit set up before you spread the chocolate/peanut butter mixture over the top. If the marshmallows are not set when the chocolate/peanut butter mixture is poured over the top you may have to mix the two layers together. The bars end up tasting delicious, but the marshmallows are not longer gooey. I ended up receiving many compliments after this mistake!