1 box white cake mix
3 eggs
1 2/3 cup mashed ripe bananas (3-4 large)
1/3 cup vegetable oil
Preheat oven to 350 degrees.  Grease a 13 x 9 pan.
In large bowl, combine all the ingredients.  Beat on medium for 2 minutes, until smooth.  Spread in pan and bake for 35 - 40 minutes.  Cool before frosting.
Banana Cream Frosting:
1/2 cup butter, softened
1/2 cup mashed banana
4 cups of sifted powdered sugar
1 T half and half or milk
In mixer bowl, beat butter, banana and half of the sugar until light.  Add half and half.  Add remaining sugar and beat until smooth.