1 package (2-layer size) Devil’s food cake mix
1/2 cup water
1/4 cup unsweetened cocoa powder
1/4 cup vegetable oil
1 Tablespoon vanilla extract
Preheat oven to 350 degrees F.
Beat cake mix, water, cocoa powder, oil, eggs and vanilla in large bowl with electric mixer on low speed just until moistened, scraping sides of bowl frequently. Beat on medium speed 2 minutes.
Spoon 1 tablespoon of batter, 2 inches apart, onto parchment paper-lined baking sheets. I use a 1 tablespoon scoop. (Cookies will spread so avoid crowding them on baking sheet.)
Bake 8 minutes or until cookies are puffed and spring back when touched. Cool on baking sheets 1 minute. Remove to wire racks; cool completely. (You’ll get about 48 cookies to make 24 whoopie pies.)
7 ounces (about 1 1/2 cups) Marshmallow Crème
3/4 cup butter, softened
2 Tablespoons water
1 1/2 to 2 cups powdered sugar
In a large bowl, beat the marshmallow crème and butter until well mixed. Add the water. Mix until combined. Beat in the powdered sugar until light and fluffy (about 2 to 4 minutes).
When cookies are completely cool pipe frosting onto the flat side of one whoopie pie and place another on top.
I place the whoopie pies, rounded side down onto a cookie sheet. Then I put the frosting into a gallon sized Ziploc bag and cut a small snip (about 1/2 inch) off the bottom corner. I squeeze frosting onto half of the whoopie pies. Then I place the other whoopie pies flat side down onto the filling and press down slightly.