1. Melt the butter. Add the marshmallows. Continuously stir until fully melted. Add the cereal. Stir well. Transfer into prepared pan. Cover top with a sheet of parchment paper and gently press down to form an even layer. Let cool completely.
2. Melt the chocolate chips. Using a large spoon, drizzle over the cooled bar. Let set.
3. Lift the bar as one piece. Slice into individual bars. Serve and enjoy!