Preheat oven to 350 degrees. In a 9 x 9 pan, cover with foil or parchment paper and spray with cooking spray; set aside. In a large bowl, mush banana then whisk together eggs, milk, water, oil and sour cream. Stir in cake mix and pudding, batter will be thick. Pour into cake pan and baking in oven for 40-50 minutes or until a toothpick inserted into the center comes out clean. Foil may be placed over the top the last 20 minutes of baking to prevent too much browning.