I'm going to give y'all the cheaters version to making whoopie pies (if you don't already make them this way yourself). Making baked goods totally from scratch is always wonderful if you have time, but honestly, making whoopie pies can be a bit tedious even when using a boxed mix. And sometimes I have a short attention span when it comes to baking. Please note: I do not pipe frosting on anything, I always slather it on there with a knife or a spoon. I just don't have the patience for piping frosting.
I probably need to work on that. So I'm going to take the shortest route here. I will point out that I have made these before using a "from scratch" recipe by Cook's Illustrated (a printable recipe for those will be on bottom of this post). They were very tasty and they came out very thick. However, I have to say, the ones from the box mix come out just as good (the cakes are a bit thinner), and it really is the filling that makes these so good, and we're going to make the filling from scratch.
(for the cakes)
1 box of devil's food cake mix
eggs, oil, and water (in quantities indicated on back of box)
(for the filling)
1-½ stick (12 Tbsp) unsalted butter, room temperature
1-¼ cup confectioner's sugar
1-½ teaspoon vanilla extract
⅛ teaspoon table salt
2-½ cups marshmallow fluff
Green food coloring (optional)
Preheat oven to 350F degrees. Line cookie sheets with parchment paper, or spray with nonstick spray. I like the parchment paper because it makes cleaning up easier later. Or if you have a silpat, use that. Prepare cake mix according to package directions. Using a spring-release cookie scoop, scoop up batter and release into small mounds onto cookie sheet. You should be able to get about 12 circles per sheet.
Now, using the back of your scoop, gently press down (using circular motions) on each mound until the batter spreads out a bit into slightly flatter and wider circles. Just make sure to leave enough room between each circle so batter can spread a bit while baking. Put into oven and bake for about 13-15 minutes. Cakes should feel firm and spring back when you touch them. Once all your cakes have been baked. Allow them to cool for at least 30 minutes.
Now time to make the filling.With electric mixer on medium speed, beat butter and sugar together until fluffy, about 2 minutes. Beat in vanilla and salt. Beat in marshmallow fluff until incorporated. Now add food coloring (if you're using). I used about a 1/4 teaspoon of Wilton's Kelly Green concentrated paste icing color. Scrape down the sides of the mixing bowl and continue to mix until it has reached desired color and has been fully incorporated. Refrigerate filling until slightly firm, about 30 minutes. Bowl can be wrapped and refrigerated for up to 2 days.
Dollop about a tablespoon of filling on center of flat side of half the cakes. Top with the flat side of the remaining cakes and gently press until filling spreads to edge of cake. Serve.
We like to eat these after they've chilled for a bit. I'll individually wrap them in plastic wrap or put them in a container with a lid and pop them in the fridge for an hour or so.
(Whoopie pies can be refrigerated in airtight container for up to 3 days.)
Cook's Tip: Marshmallow fluff can be a wee bit sticky to work with. Spray your measuring cups with nonstick spray to help it come out easier. Also, when you are spooning the filling onto the cakes, do the same thing. Just spray your spoon with nonstick spray and it will slide right out of there.
(this photo is the homemade whoopie pie recipe)