Whoopie Pie Cake Recipe 2 cups of Marshmallow FLUFF (or you can melt some marshmallow along with a little bit of milk) 1 1/2 tsp of vanilla extract Cream the butter and the powdered sugar . Fall in love with this easy recipe for whoopie pies. Two light discs of chocolate sponge sandwich a fluffy vanilla buttercream filling. Perfect for cake sales, packed lunch treats or making friends at the office!. Whoopie Pies are easy to make and very versatile, simply a pair of small sponge cakes glued together with a filling and, if desired, topping. Read More This entry was posted in Recipes , Sweet Recipes , Equipment and tagged whoopie pie , whoopie pies , dark chocolate , sponge cakes on 05/11/2010 by Patrick .. Need synonyms for "whoopie pie"? Here's 6 fantastic words you can use instead.. I have chaired our school bake sale for 8 years. I’ve made absolutely everything there is to make when it comes to baking. I haven’t made whoopie pies in a few years so I thought I’d give . 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..