Set the oven rack to the center position and preheat to 350ºF (177ºC).
Microwave butter until melted, about 45 to 60 seconds then let cool to room temperature. Butter can also be melted over low heat in a small pan.
Place bananas in a medium microwave-safe bowl and cover with plastic wrap. Microwave until the softened, 4 to 5 minutes.
Transfer cooked bananas to a strainer sitting on top of a bowl.
Lightly press with a fork to release the liquid but do not press the banana through. Allow the liquid to release for 15 minutes, stirring occasionally.
Collect the banana liquid, it should be about ½ to ¾ cup and transfer to a small frying pan.
Reduce the liquid over medium-high heat until it reaches ¼ cup, about 3 to 5 minutes.
Add the cooked bananas to a medium bowl and mash together with the reduced banana liquid. This should yield about 1 cup of banana puree. Make sure the puree is warm and not hot before adding to the other ingredients.
Add melted butter, eggs, brown sugar, and vanilla to the banana puree, whisk to combine.
In a large mixing bowl whisk together flour, baking soda, salt, and cinnamon.
Add the banana mixture to the flour, gently fold with a spatula. There should be just a few streaks of flour that remain.
Grease an 8 ½ by 4 ½ inch loaf pan with vegetable oil or cooking spray.
Pour the batter into the pan, and spread out evenly with a spatula.
Place the loaf pan on top of a small sheet pan.
Bake for 30 minutes, and then loosely tent the top of the banana bread with foil, it should not be touching the surface of the bread. This helps to prevent the bread from becoming too brown and creates more of a domed top.
Transfer banana bread to the oven and bake until golden brown and a toothpick inserted in the center comes out clean, 25 to 40 minutes.
Cool the bread in the pan for 10 minutes.
Release the side of the bread from the pan using a small spatula or knife. Carefully turn onto a wire rack, flip over and cool for 1 hour before serving.
Notes
Lasts 5 days in an airtight container.
This recipe was made in an 8-1/2 inch by 4-1/2 inch glass loaf pan. If you're using a darker or larger pan, check for doneness 5 to 7 minutes earlier than stated in the recipe because they tend to cook slightly faster.