Put your oven racks to the bottom third of the oven; heat to 350º F. Grease the bottom of a 9 x 5 x 3 loaf pan.
Cream the sugar and butter together in a large bowl with an electric mixer. Add the eggs and blend; then add the bananas, buttermilk, and vanilla. Beat until smooth.
Sift or stir together the flour, baking soda, and salt. Add to the banana mixture and stir until moistened. Stir in the nuts, if using.
Bake for about 50 minutes to an hour, or until a toothpick inserted into the center comes out clean. Cool 10 minutes, then remove the bread from the pan to a wire rack to cool. Cool completely.
Wrap tightly and store at room temperature for up to 3 days, or refrigerate.
Notes
Since I make these mostly at Christmas time, I make mini versions for gifts. To make grease the bottom of 10 miniatures loaf pans. Divide batter; about ½ cup each, and bake 30 minutes
Keyword banana bread made with buttermilk, buttermilk substitute, old fashioned banana bread