Preheat oven to 300°. Grease a large loaf pan and sprinkle with 2 tablespoons sugar, tapping out excess.
In a large bowl, beat butter and 1½ cups sugar with an electric mixer until light and well combined. Beat in eggs, mashed bananas, sour cream, vanilla and cinnamon. Mix in salt, baking soda and flour. Stir in nuts. Pour into prepared pan.
Bake 1 hour, or until a toothpick inserted in center comes out clean. Cool 10 minutes before removing bread from pan and cool completely on a rack. Wrap loaf in plastic wrap and store overnight at room temperature before slicing and serving.