In a large bowl, combine dry cake and pudding mixes, yogurt, egg whites and vanilla; beat on low speed for 1 minute. Gradually beat in soda.
Pour into a 13x9-in. baking pan coated with cooking spray. Bake at 350° for 20-25 minutes or until a toothpick inserted in the center comes out clean. Cool.
For frosting, combine milk and dry pudding mix in a bowl; beat on low for 2 minutes. Fold in whipped topping. Spread over cake. Store in the refrigerator.
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