Preheat oven to 350 degrees F. Grease a 9 x 3 inch loaf pan with butter. In a medium bowl, mash bananas and set aside. (They may get a bit watery, but that's OK, makes the bread more moist).
In a medium bowl combine sifted flour, baking soda and salt. Set aside.
In a mixing bowl cream butter and sugar until fluffy. Add eggs, one at a time, mixing well after each addition.
Add the flour mixture to the butter mixture alternately with the mashed bananas until combined, scraping sides of bowl.
Fold in chopped nuts by hand.
Pour batter into prepared pan and bake at 350 degrees F. for 50 - 60 minutes or until a toothpick inserted in center comes out clean.
Remove from pan immediately and cool on cooling rack.
Serve warm with butter or cool completely.
Store bread in wrapped in foil on countertop.
Notes
When greasing the loaf pan, I use the wrapper from the softened butter and then more if necessary.
I use pecans and usually use a bit more than 1/2 a cup.