In large bowl, place cereal. In small microwavable bowl, microwave butter uncovered on High about 30 seconds or until melted. Stir in espresso; add chocolate chips. Microwave on High 30 seconds; stir. Continue microwaving and stirring until mixture is smooth.
Pour chocolate mixture over cereal; toss until well coated.
In large resealable food-storage plastic bag, mix powdered sugar and cocoa.
Add cereal mixture and pound cake pieces; shake until evenly coated.
Serve in individual bowls or glasses. Top with dollops of mascarpone cheese.