Preheat oven to 350° F / 176° C. Line a half sheet rimmed baking tray with parchment or a silicone baking mat. Set aside.

In a large bowl, whisk together all purpose flour, cocoa powder, baking powder, baking soda, and kosher salt.

In a separate mixing bowl or the bowl of a stand mixer, whip butter on high speed until light and fluffy. Add the sugars, followed by the egg and vanilla bean paste, and continue mixing on medium-high speed until well combined.

Add the red gel food coloring and mix to combine.

With a rubber spatula, fold the dry ingredients into the batter. Add the buttermilk and continue folding until just barely combined.

Set aside and allow batter to rest at room temperature for 10 minutes. Scoop into a piping bag fitted with a 1/2-inch round tip.

Pipe 1-inch rounds onto prepared tray, allowing space for the cakes to spread as they bake.

With your fingertips, gently pat the top of each cake to create a smooth, evenly domed surface.

Bake in preheated oven for 12 minutes, or until cakes are well-risen, set around the edges, and spring back lightly when touched. Cool completely on tray. Repeat with remaining batter.

Pair cakes by size. Scoop frosting into a piping bag and pipe a generous dollop of frosting on the flat sides of half of the cakes.

Place a second cake on top of the frosting to create a sandwich.

Store mini red velvet whoopie pies in an airtight container at room temperature for up to 1 day, or in the refrigerator for up to 3 days.