Heat oven to 350 degrees F.Lightly grease 8x8x2-inch pan.In a medium bowl stir together water, egg, and oil. Add in cake mx until moistened. (Batter will still be lumpy)Take 2 bananas and mash them and then add into the batter. Then stir together.Take the last banana and slice it. Then gently stir in banana slices.Spoon 1/2 of the batter into pan and spread evenly. Sprinkle 1/2 of the topping over batter.Drop the remaining batter in small spoonfuls over topping layer and spread to cover.Sprinkle remaining topping evenly over batter.Bake for 33-38 minutes or until cake edges are light golden brown. For glass pan, add 5 minutes to bake time.After done baking let cool for 5-10 minutes before cutting.
1 box of Chocolate Swirl Crumb Cake Mix
1/2 cup water
2 Tablespoons oil