Preheat oven to 325°. In a large bowl, cream butter and sugar until light and fluffy, about 5 minutes. Add eggs, one at a time, beating well after each addition. Beat in vanilla. In another bowl, mix the flour, salt and baking soda; add to the creamed mixture alternately with buttermilk, beating well after each addition., Transfer to a greased and floured 9x5-in. loaf pan. Bake until a toothpick inserted in center comes out clean, 40-45 minutes. Cool in pan 10 minutes before removing to a wire rack to cool completely., In a small bowl, whisk milk and pudding mix for 2 minutes. Let stand for 2 minutes. In a large bowl, beat cream cheese and condensed milk until smooth; fold in pudding. Fold in 3-1/2 cups whipped topping., Cut cake into eight slices; arrange on bottom of an ungreased 13x9-in. dish, trimming to fit as necessary. Slice bananas; arrange over cake. Spread pudding mixture over top. Refrigerate, covered, for 3 hours. Serve with remaining whipped topping, and if desired, additional bananas.