Peppermint Whoopie Pies

These delicious lil treats were actually a mistake. I started the day making girl scout thin mints and ended with with more like fat mints. They taste very similar to thin mints but the texture was all off. Instead of being crunchy and thin they were soft and fat. Anyways, I decided to make them into whoopie pies and call it a day.
Here's the recipe for the cookie adapted from a book, Desserts by the Yard:
1.5 C Flour
1.25 C Sugar
.5 C unsweetened cocoa powder
1.5 Sticks of butter
Pinch of salt
2 egg yolks
Vanilla
2 tsp Peppermint oil
.5 tsp baking powder
.25 tsp baking soda

For the frosting:  I mixed (without any measuring) butter, powdered sugar, milk, cream cheese and marscapone cheese to a satisfactory frosting consistency. Then flash froze it so it would be easier to put in between the cookies.