Preheat the oven to 350°F (175°C). Grease a 9×5-inch loaf pan with butter or non-stick spray.
In a large mixing bowl, combine the mashed bananas, granulated sugar, and melted butter. Stir until smooth.
Add the eggs and vanilla extract to the banana mixture and mix well.
In a separate bowl, whisk together the all-purpose flour, baking soda, salt, and ground cinnamon.
Gradually add the dry ingredients to the wet ingredients, stirring just until combined. Do not overmix.
Pour the batter into the prepared loaf pan and smooth the top with a spatula.
Bake for 60 minutes, or until a toothpick inserted into the center comes out clean.
Remove the banana bread from the oven and let it cool in the pan for 10 minutes.
Transfer the bread to a wire rack to cool completely before slicing and serving.