Heat oven to 350°F.
Mix butter and sugar together until butter is blended well with the sugar.
Blend in eggs on low speed just until incorporated.
Blend in buttermilk and mashed bananas.
Mix in flour(except 2 tablespoons), baking soda, salt and baking powder.
Toss the 2 tablespoons of flour you held out with the chopped walnuts. Then blend in with rest of the batter.
Pour batter into loaf pan that has been rubbed with a folded paper towel lightly coated with oil(olive or avocado).
Bake for about 55-60 minutes or until wooden pick inserted in the center comes out clean.
Cool for 5 minutes on a cooling rack. Loosen the sides using an offset spatula and remove from the pan. Cool completely before slicing.
