Preheat the oven to 350°F (175°C). Grease a 9x5-inch loaf pan and line with parchment.
In a pot over medium heat, melt and brown your butter. Allow to cool about 10 minutes before mixing with the sugar and eggs.
In a small bowl, whisk together the flour, baking soda, salt (and cinnamon if using). Set aside.
In a large bowl, add the browned butter, brown and granulated sugars and whisk together. Add one egg at a time and whisk together. Add vanilla, and mix until smooth.
Stir in the mashed bananas.
Add the dry ingredients to the wet and gently fold until just combined — don’t overmix.
In a separate bowl, add a dash of flour to your nuts before folding them into the batter. I like to toast my nuts prior in the oven for about 10 minutes on 350°F.
Pour the batter into the prepared loaf pan.
Combine the crumb topping together in a small bowl and add on top of your bread batter.
Bake for 50–60 minutes, or until a toothpick inserted in the center comes out clean or with just a few moist crumbs.
Let cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.
