Preheat oven to 350 degrees then line baking sheets with parchment paper

In a bowl, sift your flour, then add cocoa, soda and salt together mix with a wire whisk

In a separate bowl using an electric mixer or Kitchenaid , mix the butter, shortening and sugar till it looks light and a wee bit fluffy.

Add egg, 1 tsp. vanilla and food coloring. Mix until combined.

Add flour and milk in two additions, alternating between each until completely combined.

Scoop batter about 2 inches apart on prepared baking sheet. You should have about 16 whoopee pies

Bake for 10 minutes. Remove and cool for 5 minutes before placing on wire rack to cool completely.

Frosting

Beat cream cheese and remaining 4 tbsp butter until creamy. Continue to mix on low and slowly adding powdered sugar until combined. Then add remaining 1 tsp. vanilla and mix until just combined.

Pipe frosting on half of the cookies and then sandwich them together with the other halves.