Preheat oven to 400 degrees. Add 1 pkg. lemon cake mix to mixer.
Add eggs, vegetable oil, and water to mixer.
Mix the ingredients.
Spread a piece of parchment paper across cookie sheet.
With a spoon, place mixture on cookie sheet, making them round and with space in-between each dollop.
Place in preheated 400 degree oven for 8 to 10 minutes.
In another mixing bowl, add softened butter, marshmallow creme, powdered sugar, softened cream cheese, vanilla extract, and salt.
Mix.
Once cookie cakes have been removed from the oven and cooled, place half of the cookie cakes on a serving plate and carefully flip each one over and spread the marshmallow mixture across each individual cookie cake.
Once you’ve spread mixture across the flat surface of one cookie cake, place another on top to complete the whoopie. Repeat until all whoopies are made.