For the cake, cream the butter and sugar until light and fluffy.
Beat in eggs, bananas and vanilla.
Combine flour, baking soda, baking powder and salt into a separate bowl.
Add the dry ingredients to the creamed mixture alternating with the buttermilk beating well after each addition.
Pour into greased and floured bread pan.
Bake at 375 degrees for about 30 minutes or until toothpick comes out clean.
While baking, cream together butter and cream cheese for frosting. Slowly beat in powdered sugar and vanilla until well combined.
When cake is done, cool for 10 minutes before removing to wire rack to cool completely.
Frost with cream cheese.