Preheat the oven to 350 degrees. Butter and flour a large 9x13-inch baking dish.
Using a hand mixer or stand mixer, beat all ingredients except egg whites in a large bowl on low speed for 30 seconds, scraping the bowl.
Add the egg whites and beat on high speed for 2 minutes, scraping the bowl.
Fold chocolate chips into the batter. Pour into the prepared baking dish.
Bake for 35-40 minutes, or until a toothpick inserted in the center comes out clean, or until the cake springs back when touched lightly in the center.
Let the cake cool completely on a wire cooling rack before frosting.
Carefully frost the cake, then decorate it the way you or your little ones desire.