Melt the butter in a large sauce pan on medium heat. Once melted, stir in the entire bag of marshmallows, mixing occasionally until the marshmallows are melted and the mixture is complete smooth. Then, remove the saucepan from the heat, and mix in the 6 cups of Rice Krispies cereal until completed coated in marshmallow.

Transfer the cereal-marshmallow mixture into a 13"x9" pan, and pat until smooth, and let the treats cool for about an hour, before cutting into rectangles. Prepare a pan with parchment paper to put the finished treats on, and set aside.

Place the chocolate chips in a microwave-safe bowl and heat for one minute. Stir the chocolate chips, and place back in the microwave for 10 seconds intervals until the chocolate is smooth and melty. Dip each Rice Krispie Treat halfway into the melted chocolate mixture, and sprinkle some Mini M&M's on top. Place each treat on the parchment paper. Let them cool until the chocolate is completely cooled, about 30 minutes.