For the red velvet whoopie pies:

1. Preheat the oven to 350 degrees F and line two large baking sheets with parchment paper. Create a template by tracing 2" circles, spaced about 1" apart, onto a separate piece of parchment paper.
2. In a medium bowl, combine the flour, black cocoa powder, baking powder, baking soda, and salt. Set aside.
3. In a glass measuring cup, combine the buttermilk, white vinegar, and food gel. Set aside.
4. In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and sugar for 2-3 minutes until light & fluffy.
5. Mix in the egg and vanilla. Scrape down the bowl to ensure everything is fully combined.
6. Add half of the dry ingredients and mix until just combined.
7. Mix in the buttermilk mixture, then the remaining dry ingredients until just combined.
8. Transfer the batter to piping bag with a medium piping tip (I used Ateco 806).
9. Place the template under the parchment paper on the baking sheet. Pipe the batter perpendicular to fill in each circle. Gently pat down the points with your finger, then remove the template and repeat until all of the batter has been piped.
10. Bake the whoopie pies for about 8 minutes. Allow to cool completely on the baking sheet.

For the cream cheese frosting:

1. In the bowl of a stand mixer fitted with a paddle attachment, beat the butter and cream cheese on high speed until smooth.
2. Slowly add the sifted powdered sugar and mix on low speed until fully combined.
3. Once all of the powdered sugar is added, continue beating on low speed until no more lumps or pockets of air remain and the frosting is smooth.

For assembly:

1. Pair the whoopie pies up. Transfer the cream cheese frosting to a piping bag with a small round piping tip (I used Ateco 804).
2. Pipe the frosting onto the bottom whoopie pie and gently press the paired one on top.
3. Serve room temperature or chilled. Enjoy!