Add soda to buttermilk; stir to mix and set aside. Soften butter in microwave and stir in sugar; add eggs and beat until smooth. Add buttermilk mixture and bananas; stir to mix. Add flour and salt and beat until smooth. Stir in vanilla and pecans. Pour into 9 X 13-inch prepared baking pan. Bake at 350F for 35-40 minutes or until cake tests done. Frost with Banana Frosting.
1/2 c butter or margarine, softened
1 (16-oz) box confectioners sugar
1 ripe banana, mashed
1/2 cup chopped, toasted pecans, optional
Combine ingredients in a bowl and mix together and beat until smooth. Spread on top of cake.