Preheat oven to 350 degrees. Spray a 13x10 inch baking pan with cooking spray and set aside.
In a large bowl, mix together the cake mix, Greek yogurt, and water. Mix vigorously for 1 minute. Pour mixture into prepared baking pan and bake in the preheated oven for 25-35 minutes. Mine was ready at 25 minutes. Cool completely on a wire rack.
In a medium sized bowl, stir together the pudding mix, milk, and vanilla extract until thickened. Fold in the whipped topping. Spread frosting over the top of cooled cake and add mini chocolate chips if desired. Enjoy!