Preheat oven to 350 degrees. Butter the loaf pan.
Cream the sugars and the butters together (different butters give different flavors). Add eggs and mix well.
Sift flour, salt, and soda together. Blend a little at a time, alternating flour and buttermilk into the sugar mixture. Add bananas.
Pour into loaf pan. Bake 60 minutes or until a knife runs through it well.