Stir food color into each as desired to create rainbow colors. Stir until well blended. Spoon batter into individual resealable food-storage plastic bags. Cut 1/4 inch off corner of each bag. Onto cookie sheets, squeeze each bag of colored batter gently to make 20 1/2-inch circles of dough (about 1/4 teaspoon each), about 1 inch apart.. This Wilton pie pan features 12 cavities, allowing you to create six whoopie pies. The tray also allows you to make ice cream sandwiches and macarons our of your favorite ingredients, such as chocolate, pumpkin or gingerbread.. 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.. 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!. The Wilton Nonstick 12-Cavity Whoopie Pie Pans should be filled with 1/8 cup (2 Tbsp) of batter per shell, and the 24-cavity mini pans take half that much batter. So you may get fewer, or more, than 36 filled pies out of this recipe Also, although they freeze beautifully, if you don't want to bake that many, you can cut the recipe in half.. Scoop batter onto whoopie pie pan 2/3 way full. Bake for about 10 minutes each or until pies spring back when pressed gently. Remove from oven and cool completely. Bake for about 10 minutes each or until pies spring back when pressed gently..