What I did was that I mixed together hazelnut creme, butter, a little bit of confectioners sugar and a tiny bit of milk into a semi-soft creamy mix. My plan was to cut a hole in the middle of the cupcake and fill them with the mix, and so I did. I then finished them off by piping the top with a new frosting recipe that I wanted to try. It worked alright. The cupcakes now tasted great and with the filling got a much lighter and moist texture. However I wasn't quite satisfied with the frosting - it tended to collapse slightly. As I was feeling naughty I tossed the hazelnut mix into my frosting and lo and behold! It worked great. I successfully made a nice looking frosting, with a nice texture and a good hazelnutty flavor which also held together great. Im proud!