In a large bowl, cream butter and sugar until light and fluffy. Add the eggs, sour cream and vanilla.
Combine flour, baking soda and salt; gradually to creamed mixture. Stir in the bananas.
Spread into a greased 15-in.x 10-in.x 1-in. baking pan. Bake at 350° for 20-25 minutes or until a toothpick inserted near the center comes out clean. (Do not overbake). Cool.
Frosting: In a mixer beat cream cheese , butter and vanilla until fluffy. Gradually beat in enough confectioners' sugar to achieve desired consistency.
Frost Bars.
Store any leftovers in refrigerator.
Recipe by Clever Housewife at https://cleverhousewife.com/2012/07/frosted-banana-bars/