Whoopie Pie

Whoopie pies have parallel claims from Pennsylvania Dutch country and Maine. Pennsylvania folklore says Amish women shouted whoopie when they found one in their husband's lunch pail; the Maine version became commercial in the 1920s when Labadie's Bakery in Lewiston put them in production. Maine made it the official state treat in 2011 (the state dessert is blueberry pie). Berwick Cake Company of Roxbury, Massachusetts also claimed early commercial production.

Two parallel claims: Pennsylvania Dutch country and Maine. Labadie's Bakery in Lewiston, Maine put it into commercial production in the 1920s; Maine made it the official state treat in 2011. Baking soda reacting with buttermilk's lactic acid is what gives the cake its dent-under-a-fingertip softness.

A puck the size of a hockey puck, two domes of dark cocoa cake almost like a thick madeleine, with a 2cm slab of pure-white marshmallow filling pushing out at the seam. Bite is soft into soft — no crackle, no crunch. The cake reads cocoa-bittersweet; the filling is almost cloyingly sweet, marshmallow-vanilla, with a buttery slick on the tongue. Eaten cold from the fridge or warm from a lunch pail. A bad whoopie pie is dry, dense, or has crumbled — the cake should be tender enough to dent under a fingertip.

The cake uses baking soda (not powder) reacting with buttermilk's lactic acid — that combination produces fast, soft rise without the bitterness of unreacted soda. Brown sugar's molasses keeps the crumb moist for 2 days. The marshmallow-buttercream filling is structurally a buttercream stabilized by the marshmallow's gelatin and sugar matrix — pure American buttercream alone would weep into the cake; pure marshmallow alone would slide out the sides.