Cream butter and sugar in an electric mixer. Add eggs, baking soda and sour cream. Mix well. Finally add bananas, flour and vanilla and mix until all ingredients are combined.
Place in a well greased loaf pan. Bake at 350* for 50 minutes to 1 hour. Place on cooling rack to cool.
I have a filling that my mother used to make. It will be called Mom's Banana Bread Filling. She would make bite size sandwiches using the filling and serve at bridge. (These little sandwiches should be kept in the refrigerator.)