In Juniata, Perry, and Dauphin counties they are called Whoopie Pies. Don't know about tasty goodness 'cause I've never eaten one -- and don't plan to, either. 'Sitting broad' is not part of the Pennsylvania lifestyle I am willing to embrace
From the 50s I remember a packaged commercial product sold in the NYC metro area (more of a cookie-like chocolate part, though, than a cake -- with a similar filling) were called Scooter Pies. Less fatty than the original, it was just a grossly sweet snack -- and we loved them!