Grease & flour two 9 inch round pans, set aside. Preheat oven to 350 degrees Fahrenheit.
In a large bowl combine cake mix and strawberry Jell-O mix until completely mixed. Then add egg whites and oil. Beat until well blended.
In a small bowl or food processor, mash strawberries. Set aside 3 Tablespoons for icing. Add water and remaining berries to batter and mix. Pour into prepared pans.
Bake in preheated oven at 350 degrees Fahrenheit for 20-25 minutes or until a toothpick comes out clean when inserted into the middle of the cake. Cool for 10 minutes. Remove from pans to wire rack and cool completely.
To make frosting combine butter and 3 Tablespoons reserved strawberries in a small bowl. Gradually beat in powdered sugar until light and fluffy.
Place one of the cooled round cakes on a serving platter. Top the cake with half of the icing. Then place the other round cake on top of the frosting. Finish frosting the outside of the cake.
