1 (18-1/4-ounce) package yellow light cake mix 2 (1-ounce) packages instant sugar-free vanilla pudding mix -- divided 4 egg whites 1 cup water 1/4 cup vegetable oil 1/4 teaspoon baking soda 1 cup cold skim milk 1 (8-ounce) carton frozen light whipped topping -- thawed 1 (20-ounce) can...