In a mixer beat together butter, brown sugar, eggs, and vanilla extract. Mix till light and fluffy.
To the butter mixture add the flour, baking powder, baking soda, and salt. Mix again.
To the flour mixture add buttermilk and mix.
Than add the ripe bananas to the buttermilk mixture and mix.
Oil a 9 x 13 glass pan.
Bake at 350 degrees for 25 minutes.
Let the cake cool for 10 minutes.
To make the icing use a stand up mixer and add softened butter, salt, cream cheese, and ripened bananas. Than add the powdered sugar, lemon juice, and vanilla extract. Mix well If frosting is not thick enough add a little powdered sugar.
Than frost your cake and add the nuts you are done!