preheat oven to 350. Grease 2 round 9 " pans. In a large mixing bowl, combine cake mix, water, oil, and 3 egg whites withan electric mixer for 2 minutes. Gently stir in crushed cookies. Pour batter evenly between the 2 prepared pans. Bake 25-35 minutes. Cool 10 minutes. Remove from pans and cool completely.
To make frosting:
In a small bowl, Blend 1/2 cup powdered sugar, shortening, vanilla, and 2 egg whites. Add 2 1/2 cups powdered sugar slowly until creamy. Frost cooled cakes. place one of the cakes on the other to make a layered cake. Garnish with cookies on the top.