Preheat oven to 350 degrees. Butter and flour a large loaf pan or 4 mini loaf pans.
In a medium bowl, whisk flour, salt, baking soda and baking powder together. Cream butter and sugar in a stand mixer until pale and fluffy, about 2 minutes. Add in eggs, sour cream, vanilla and mashed banana until fully combined. With mixer on low add in dry ingredients in 3 batches until just combined. Batter will be thick. Pour it into your prepared pan(s) and bake for 55 - 60 minutes for a large loaf pan until a toothpick comes out clean.
by The Savvy Kitchen