Change the oven to 350℉ (175℃). Grease and line a 9x5 loaf form with parchment paper.
In a medium bowl, combine the flour, baking soda, baking powder, and salt.
In a large mixing bowl, beat together the brown butter with the sugars for 2 minutes with an electric mixer.
Scoop out the soft bananas and toss into the batter on low speed until the bananas are broken up and mixed in.
Crack in the eggs, mixing on medium speed inbetween each egg until incorporated.
Scrape down the sides of the bowl and whisk in the espresso and the vanilla until just combined.
Sift in the dry ingredients and fold gently. Do not overmix.
Pour into the prepared loaf form.
Slice the last banana lengthwise and place on top of the loaf.
Bake for 40-45 minutes or until a skewer comes out with crumbs and no wet batter.
Place a kitchen towel on top and allow to cool completely before taking out from its form.
Slice into thick pieces once cooled and enjoy!