Preheat oven to 350 degrees. Grease and flour a loaf pan. Sift flour, baking powder, baking soda and salt into a large bowl and mix thoroughly, set aside.
In another bowl mash bananas, egg, sugar, cinnamon, nutmeg, cloves, butter and vanilla together and mix thoroughly. Slowly add dry ingredients into wet ingredients and mix well. Once the batter is well combined add walnuts and stir. Pour ingredients into prepared loaf pan. Bake in the oven for 40-45 minutes or until a knife inserted into the center comes out clean. Remove from oven & let cool for a few minutes before cutting. Serve while it's warm with butter.