Line a 9×13” pan with foil, and spray the foil with non-stick cooking spray. (Keep the cooking spray close by; you’ll need it later).
Measure out the dry cereal into a large bowl before setting aside.
Combine butter and marshmallows in a large pot over medium heat, stirring frequently until both are melted and are well combined. Stir in the hot chocolate mix, stirring to incorporate thoroughly into marshmallow-butter mixture. Stir in the krispie cereal and pour into prepared pan.
Working quickly, spray your hands with cooking spray so they won’t stick to the marshmallow cereal mixture, and carefully press the treats into the pan. (Be careful – the molten marshmallow mixture will be very hot.) Sprinkle the Mallow Bits and mini chocolate chips immediately onto the top of the rapidly-cooling cookies, pressing lightly to secure them to the top of the krispie treats.
Allow to cool completely before cutting into squares.