Preheat the oven to 350°F.
Line a 9"x5" bread pan with parchment paper and grease.
In a small bowl, sift together flour, cinnamon, baking soda, and baking powder. Set the dry ingredients aside.
In a large bowl, beat sugar and eggs with a handheld mixer until light and fluffy.
Beat the mashed bananas into the egg mixture. Whisk in sour cream, vinegar, maple syrup, oil, and vanilla.
Fold the dry mix into the wet batter and mix in ½ cup of nuts.
Pour the mixture into the bread pan and sprinkle the top with extra nuts.
Bake in the oven for 30 minutes. Turn the heat down to 325°F and bake another 25-30 minutes.
Allow the loaf to cool slightly before removing from the bread pan. Let the loaf cool completely on a wire rack before glazing.