Is it a cake? Is it a cookie? With such deliciously soft and sweet cream-filled snacks, does it matter? The Internet is abuzz with recipes and stories of whoopie pie folklore, while customers everywhere are descending on bakeries in droves demanding these delectable treats. This adorable volumethe only cookbook devoted entirely to whoopie piesfeatures more than 40 mix-and-match recipes, including the classic chocolate with marshmallow cream and a...