First, preheat the oven to 350℉ then brown your butter so that it can cool. If you've never browned butter before I linked a short video above in the blog post.
Mash up the bananas. This recipe will take around 2 large or 3 small bananas to give you the proper measurements. Whisk in the sugar into the mashed banana. Add in the vanilla, egg and lastly the cooled brown butter.
In a separate bowl, add in the flour and the baking soda. Combine the dry and the wet until just combined, don't over-mix.
Pour the batter into a lined loaf pan. Place in the oven for 55 minutes. Keep an eye on it around this time because ovens vary. You may need less or more time.
Allow the browned butter banana bread to cool, then slice, serve and enjoy.