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.. Yield: 8 large whoopie pies (about 4" dia., about 5 ounces each). To make smaller pies, see ** in step 7. To make smaller pies, see ** in step 7. Due to the differences between natural and Dutch-processed cocoa powders, do not substitute one for the other in recipes.. 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 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 . #HowItsMade Mondays 9/8c on Science This Whoopie Pie factory has a variety of delicious ingredients that give these traditional treats their signature taste.. Whoopie Pie Recipes Looking for whoopie pie recipes? Allrecipes has more than 20 trusted whoopie pie recipes complete with ratings, reviews and baking tips..