Preheat oven to 350 degrees. Prepare cake mix as directed on package. Pour batter into a greased 13x9 inch pan.
Pour milk and water into large bowl. Add dry pudding mixes and granulated sugar. Beat with wire whisk 2 minutes or until well blended. Pour over cake batter in pan. Place baking pan on a cookie sheet to catch drippings.
Bake 55 minutes to 1 hour or until toothpick inserted in center comes out clean. Cool in pan 20 minutes. Mixture will thicken slightly as it cools. Sprinkle with powdered sugar. Serve warm or or at room temperature.