Pre-heat oven to 350. Line a loaf pan with parchment paper. Mix the flour, baking powder, cinnamon and salt together. Mash the bananas. Stir the sugar and oil into the bananas. Mix the dry ingredients into the wet then stir in the nuts. Leave a few nuts out to sprinkle on top. Pour into a lightly greased loaf tin and bake for 50-55 minutes. Let it cool for 10 minutes before slicing