Yes, that filling would be great in cupcakes. I'm not sure why the recipe calls for boiling the milk and cocoa. Maybe the cocoa powder blends in better when it's heated to boiling?That peanut butter filling . Bet that would great piped into cupcakes. I used an old bread bag to pipe it--wasn't a great idea
What's the point of heating the milk and cocoa to boiling though? That was the fussiest part of the recipe