Heat oven to 350° F.
Peel, slice and mash ripened bananas; set aside.
In large bowl, beat butter and sugar until fluffy. Add eggs, sour cream and vanilla; blend well. Gradually add in flour. Stir in bananas. Add baking soda and salt; mix well.
Pour batter into baking pan. Bake 20-25 minutes, or until toothpick inserted into center of cake comes out clean. Let cool.
To make frosting: In large bowl, beat cream cheese, butter and vanilla extract until fluffy. Gradually add powdered sugar. Mix until well combined.
Frost cake. Store in refrigerator until ready to serve.