Heat oven to 180C/160C fan/gas 4 and line baking trays with parchment. Mix flour, cocoa, bicarb, sugar and a pinch of salt. Whisk the egg, oil and buttermilk together, then mix into dry ingredients with 75ml boiling water.. Cooking Recipes / Chocolate Whoopie Pie Cake . Chocolate Whoopie Pie Cake is a delicious spin on the classic whoopie pie! A dense chocolate cake filled with a soft and pillowy marshmallow filling . A bit too big for a whoopie pie, and the fondant icing on top is unnecessary and very DIY, but an overall delight, especially the tangy filling. Harrods (£2.50 each, or £1.25 for a mini whoopie . L.D. 71, officially known as "An Act to Designate the Whoopie Pie as the State Dessert", read "The whoopie pie, a baked good made of two chocolate cakes with a creamy frosting between them, is the official state dessert".. Here's what all the fuss about Whoopie Pies is about - and this recipe won't disappoint! What could be better than combining chocolate cake, with a creamy filling.. #HowItsMade Mondays 9/8c on Science This Whoopie Pie factory has a variety of delicious ingredients that give these traditional treats their signature taste..