1 Duncan Hines Classic Yellow Cake Mix
1/8 tablespoon baking powder
1 egg
3/4 cup water
3 bananas, overripe, mashed (about 1 cup)
2 tablespoons walnuts, crushed (optional)
Vanilla Cream Cheese Frosting
6 tablespoons cream cheese
2 tablespoons unsalted butter
2 tablespoons whole milk
1 3/4 cup powdered sugar
1/8 teaspoon Salt
2 tablespoons vanilla extract