1Heat oven to 350°F. Grease bottom only of 9x5- or 8x4-inch loaf pan.
2In large bowl, beat sugar and butter with electric mixer on medium speed until light. Add eggs; beat well. Stir in bananas, buttermilk and vanilla; blend well. Stir in flour, baking soda and salt just until moistened. Stir in walnuts. Pour into pan.
3Bake 50 to 60 minutes or until toothpick inserted in center comes out clean. Cool 5 minutes in pan on cooling rack.
4Loosen sides of loaf from pan; remove from pan, and place top side up on cooling rack. Cool completely, 1 to 2 hours, before slicing. Wrap tightly, and store at room temperature up to 4 days, or refrigerate.