Measure out the cereal and put it into a large bowl.
In a medium saucepan over low heat melt together the chocolate, marshmallow fluff, and butter. Stir consistently until well combined. If it is not smooth, remove from the heat and whisk until smooth.
Pour over the cereal and stir until the cereal is well coated.
Pour into a large container and top with the powdered sugar. Cover the container and toss until the pieces are well coated with powdered sugar. Pour out the mixture onto a baking sheet in a single layer and allow to cool completely.
Return the mixture to the container and add the graham cracker pieces, marshmallow, bits, and mini chocolate chips. Toss to combine. Store in an airtight container for up to two days. Best when served immediately.