Using a bowl to mash the bananas, whisk in the egg into the bananas. Next, add in the butter, sugars and vanilla extract. In a separate bowl, pour in the flour, baking soda, salt and the cinnamon. Now, combine the dry and wet ingredients.
Fold in the oats then pour the batter into a lined loaf pan. Place the pan into the oven and bake 50 minutes or until the bread is finished cooking.
Allow the banana oat bread to fully cool before slicing then serving.