Preheat your oven to 350 degrees Fahrenheit.
Grease a 9 by 5 inch loaf pan with butter or non-stick spray.
Whisk the flour, baking soda, salt, and cinnamon together in a large bowl.
Stir the mashed bananas, melted butter, brown sugar, eggs, and vanilla extract together in a separate medium bowl until combined.
Pour the wet ingredients into the dry ingredients.
Stir with a spatula just until the flour streaks disappear.
Pour the batter into the prepared loaf pan and smooth the top.
Bake for 55 to 65 minutes.
Tent the loaf loosely with aluminum foil if the top browns too quickly before the center is set.
Check for doneness by inserting a toothpick into the center; it should come out clean.
Cool the bread in the pan for 10 minutes.
Transfer to a wire rack to cool completely before slicing.