Jenny's Whoopie Pies

This recipe is from my neighbor.
Our daughters are in K together, and this is their 3rd year going to school together. Coincidentally, our babies are also the same age and are in preschool together now. Jenny told me about her Whoopie pies, and I got the recipe from her in November, but am only now getting the recipe up?
I still haven't made these.
I think I am scared of them.
Scared that I will love them, and never stop making them, and only get fatter than I already am! :D
(If you are someone that looks at my other blog too, this is the neighbor in the house in the field, often pictured in the header photos of the sunsets from my porch. Go look now: www.sustainablemaine.blogspot.com)

Ingredients
2 cups shortening
2 cups sugar
4 eggs, separated
4 cups flour
10 Tablespoons cocoa powder
2 teaspoons baking powder
2 teaspoons baking soda
Salt
2 cups milk
Vanilla
4 cups confectioners sugar

Process

• Preheat oven to 350
• Cream together 1 cup shortening and 2 cups sugar.
  
• Add 4 egg yolks and mix well.
  
• In a separate bowl sift together flour, cocoa powder, baking powder and soda, and 2/3 teaspoons of the salt (yes, it says 2/3- I don't know why- just eyeball it.)
  
• Add the dry mixture to the sugar mixture and add 2 cups milk and 1 teaspoon vanilla.
  
• Drop by the heaping Tablespoons onto a cookie sheet (depending on how big you like your pies)
• Bake for 10-15 minutes
  
• To make filling, in a bowl with mixer add 1 cup shortening, 4 egg whites, 4 cups confectioners sugar, dash vanilla, dash salt and beat until fluffy.
  
• Make sure cakes are cool before filling.

I have found they store best if you individually wrap each one in a baggy. If I have cake left over sometimes I fill them with coffee ice cream for a later treat.