Melt chocolate chips, butterscotch chips, peanut butter, corn syrup & butter over medium heat, stirring constantly.
Measure 8 c. Chex cereal into a large paper grocery bag.
Pour melted chocolate mixture over cereal, close bag, and shake vigorously until cereal is evenly coated.
Add 1 c. powdered sugar; shake to coat. Add another 1 c. powdered sugar; shake to coat.
Spread out on a large baking sheet to dry. Store in a sealed container at room temperature.