PREHEAT oven to 350°F. Prepare cake batter as directed on package; pour into greased 13x9-inch baking pan.
POUR milk and 2 cups water into large bowl. Add dry pudding mixes, sugar and cinnamon. Beat with electric mixer on low speed 1 to 2 minutes or until well blended. Pour over batter in pan.
BAKE 1 hour or until toothpick inserted in center comes out clean. Cut into 24 squares to serve. Or, spoon into serving dishes. Serve warm.