For the Red Velvet Whoopie Pies

1. Preheat your oven to 350 degrees Fahrenheit. Line baking sheets with parchment paper to ensure the whoopie pies come off of the pan cleanly after baking and cooling.
2. In a medium bowl, whisk all purpose flour, baking powder, baking soda, salt, and cocoa powder together until combined.
3. In a large bowl, whisk vegetable oil, granulated sugar, light brown sugar, room temperature buttermilk, room temperature egg, and vanilla extract together until smooth.
4. Add dry ingredients to your large bowl of wet ingredients and whisk until you see all pieces of the flour mixture disappear into the batter. The batter will be thick and may look slightly lumpy, but you should not see any of the dry ingredients along the sides of the bowl or poking through the batter.
5. Add the distilled vinegar and red food gel to the batter. Whisk until incorporated but try to add the food gel in as few additions as possible to prevent overmixing the batter. Doing so could lead to flatter and drier whoopie pies.
6. Spoon the batter into slightly larger than 1/2 tablespoon dollops at least 2 inches apart on your prepared baking sheets. The cake disks will rise and spread as they bake, so make sure there’s enough room between your circles of batter.
7. Bake the whoopie pies for 7-10 minutes or until the tops look domed, centers look just slightly soft but set, the tops spring back when quickly poked in the center, and a toothpick inserted into the center comes out with a few moist crumbs.
8. Allow the whoopie pies to cool on the sheet pans for about 10 minutes before transferring them to a parchment or plastic wrap-lined plate. The whoopie pies are sticky and will likely get stuck to each other or any surface without parchment or cling wrap.
9. Let the whoopie pies fully cool before filling.

For the Cream Cheese Frosting

1. In a large bowl with an electric hand mixer or in a stand mixer that is fitted with a paddle attachment, beat room temperature butter and room temperature cream cheese together on high speed until smooth. This should take about 3 minutes of mixing to add air to the frosting.
2. Carefully, mix the powdered sugar into your frosting in multiple, small additions to avoid spilling. Beat on medium speed until fully smooth and incorporated.
3. Add marshmallow fluff to the cream cheese frosting, making sure to scrape down the sides and the bottom of the bowl with a rubber spatula before continuing to mix. This will ensure all of the ingredients are properly incorporated with one another. Beat on medium-high speed for 2 minutes to create a light, airy, and velvety frosting.

For Assembly

1. If desired, transfer frosting to a piping bag, large zippable bag that you can cut the corner off of, or a parchment triangle for greater control.
2. Top half of the whoopie pie disks on their flat side with frosting.
3. Place one whoopie pie disk flat-side-down on top of the frosting to create a sandwich. Repeat with remaining cake pieces to create whoopie pies.
4. Store whoopie pies individually wrapped in cling wrap, layered between pieces of parchment paper in an airtight container, or in a single layer on a parchment-lined plate or baking sheet that is covered with cling wrap or aluminum foil in the fridge for up to 4 days or in the freezer for up to 3 months.