1Heat oven to 350°F. Make and bake cake mix as directed on box for cupcakes, using water, oil and eggs. Cool completely.
2Meanwhile, make pudding mix as directed on box, using 1 1/2 cups milk. While pudding is hot, stir in 1/2 cup of the chocolate chips until melted. Cover; refrigerate until cool, about 1 hour.
3Place remaining 2 cups chocolate chips in heatproof bowl. In 1-quart saucepan, heat whipping cream to boiling. Pour over chocolate chips; let stand 1 minute. Stir with whisk until melted and smooth. Let ganache stand at room temperature 30 minutes, stirring occasionally, until thickened.
4Crumble 1 cupcake; set aside for topping. With end of wooden spoon handle, make deep, 3/4-inch-wide indentation in center of top of remaining 23 cupcakes, not quite to bottom. Spoon pudding into resealable food-storage plastic bag; seal bag. Cut 1/2-inch tip off corner of bag. Insert tip of bag into opening in each cupcake; squeeze bag to fill opening. Frost cupcakes with ganache; sprinkle with cupcake crumbs. Store loosely covered.