Northern slang for a cake with a cream filling. The most common is chocolate cake with white frosting (think Hostess cakes, but with each bakery having a homemade tweak). But I've seen other cakes with other fillings like jelly still called "whoopie pies".
“What is a ‘whoopie pie’?................
Northern slang”
I’m in New York, is that NORTH enough? I’ve NEVER heard of a ‘whoopie pie’.
The best Whoopie Pies are made by the Ohio Amish.
https://www.maryyodersamishkitchen.com/product-detail/62/