In a large mixing bowl, mix the flour, cocoa powder, salt, and baking powder.
Then mix in the butter, brown sugar, egg, buttermilk, and vanilla extra. Mix well. Then add a few drops of the red food coloring, just enough to get a red color, mix well so the color is even through the mixture.
Spray your whoopie pie pans with non-stick cooking spray. Fill the cavity about 2/3 the way full. Set the pan into the air fryer at 320 degrees F for 15-18 minutes. (air fryer setting)
Let the whoopie pies cool while you make the filling.
To make the filling, in a large mixing bowl, mix the cream cheese, butter, vanilla extract, and powdered sugar, continue to mix until smooth.
To assemble the whoopie pies, add about 3 tablespoons of filling onto one side of the whoopie pie, and then use another to cover the filling. Making a sandwich.
Plate, serve, and enjoy!