| Preheat oven to 350°F |
| Grease and flour a 9x13-in pan |
| Soften the butter and cream cheese |
| 3/4 cup unsalted butter, softened | cream until fluffy | beat in one at a time | mix in alternately | bake 350°F 30 to 40 min, until a toothpick comes out clean | cool completely | spread over cake |
| 1 1/2 cups sugar |
| 3 large eggs |
| 1 tsp vanilla extract |
| 2 1/2 cups all-purpose flour | whisk |
| 1 tsp baking soda |
| 1 tsp baking powder |
| 1/2 tsp table salt |
| 1 1/2 cups (about 3) very ripe bananas, mashed |
| 1 cup buttermilk |
| 8 oz cream cheese, softened | beat smooth | beat in until fluffy |
| 1/2 cup unsalted butter, softened |
| 1 tsp vanilla extract |
| 3 1/2 cups powdered sugar |