Preheat the oven to 350 degrees F. Grease the bottoms of two loaf pans with nonstick spray.
In a large bowl, cream together the sugar and softened butter until combined.
Stir in the eggs until well blended.
Blend in the mashed bananas, vanilla, and buttermilk until smooth.
Add the flour, salt, and baking soda. Stir just until the dry ingredients are moistened.
Divide the batter evenly between the prepared loaf pans.
Bake for about 1 hour, or until a toothpick inserted in the center comes out clean.
Let the loaves cool briefly in the pans, then turn them out onto a wire rack.
Cool completely before slicing for the cleanest slices.
Store leftovers covered in the refrigerator for up to 7 days.
Notes
Use very ripe bananas for the best flavor and sweetness.If you do not have buttermilk, stir 1 tablespoon white vinegar into 1/2 cup milk and let it sit for 5 minutes.Do not overmix after adding the flour or the banana bread can turn dense.The loaves slice best after cooling for a couple of hours.