Preheat oven to 350 degrees F. Spray a large jelly roll pan (15 x 10 x 1) with non-stick cooking spray (or grease and flour - whatever method you prefer).
In a large bowl, mix together cake mix, pudding mix, sour cream, milk, oil, vanilla, and egg whites. Beat for about two minutes using electric mixer until batter is smooth.
Pour batter into prepared pan and cook for 12-15 minutes or until cake springs back when lightly touched in the center. Remove from oven and let cool.
Mix together cream cheese, powdered sugar and vanilla. Beat until smooth, then fold in the Cool Whip and stir well.
Spread cream cheese layer over cooled sugar cake. Place in the fridge for about 30 minutes to let the cream layer set up.
Top with fresh strawberries, cut, and serve.