Add the Rice Chex cereal to an extra-large bowl, ensuring it's ready to be coated with the chocolate-peanut butter mixture.
In a microwave-safe bowl, combine the semi-sweet chocolate chips, creamy peanut butter, and salted butter. Microwave on high for 1 minute, then stir well until completely melted and smooth.
Stir in the pure vanilla extract until fully incorporated.
Drizzle the warm chocolate-peanut butter mixture over the cereal in your bowl. Gently stir to ensure each piece of cereal is luxuriously coated.
Fold in the crushed Butterfinger candy bars, making sure they are evenly distributed throughout the cereal mixture.
Sprinkle powdered sugar over the mixture and stir or place everything into a ziplock bag and shake vigorously for even coverage.
Spread the mixture on a baking sheet to dry before sprinkling in chopped fun size Butterfingers just before serving.