Preheat oven to 350°F.
Coat a 9″x5″ loaf pan with butter and flour.
In a medium bowl, whisk together flour, salt, baking soda, baking powder, chocolate chips, and walnuts.
Whip room temperature butter in a large bowl. Gradually add sugar, beating until well blended. Beat in eggs one at a time, followed by the mashed bananas and vanilla extract, and finally the flour mixture.
Pour the mixture into the loaf pan and bake until a toothpick inserted into center comes out clean, about 1 hour.
Turn out onto a rack to cool.
