Cream the brown sugar and butter together with mixer on medium speed for about 1-2 minutes. Add the banana, egg, milk, vanilla, and cinnamon. Beat with mixer until well combined.
Mix in the dry ingredients until smooth.
Add chocolate chips to your liking. The more the better! Spread the batter into the loaf pan.
Bake for 1 hr and 5 minutes or until golden brown and a knife goes through clean.