In a microwave-safe bowl, combine the semi-sweet chocolate chips, creamy peanut butter, and melted butter. Microwave in 30-second intervals, stirring in between, until smooth.

Once melted and combined, pour the chocolate mixture over the Rice Chex cereal in a large mixing bowl.

Gently stir the cereal until all pieces are evenly coated with the chocolate mixture.

Add the chopped Butterfinger candy bars and stir to combine.

Transfer the coated cereal mixture to a large resealable plastic bag. Add the powdered sugar, seal the bag, and shake until the cereal is well coated.

Spread the mixture onto a baking sheet lined with parchment paper to cool.

Once cooled, serve immediately or store in an airtight container.