Preheat oven to 350 degrees Fahrenheit. Lightly spray a 9 X 11 baking pan with non-stick cooking spray.
In a large bowl, use a mixer to combine cake mix, pudding, yogurt, egg whites and water. Mix together for 2-3 minutes until well blended.
Pour batter into cake pan and bake for 35-40 minutes or until a toothpick inserted comes out clean.
While baking, combine ingredients for frosting. Use a mixer to beat milk and pudding on medium speed. Let rest for a few minutes and fold in thawed whipped topping. Place in refrigerator until cake has cooled.
Top cake with frosting. Serve or store in the refrigerator until ready to enjoy.
For a fun festive St. Patrick’s Day dessert, add some green food coloring to the batter or frosting, or both!