Instructions:
- Preheat oven to 350°F (175°C). Grease and flour a 9x5 inch loaf pan, or line with parchment paper, leaving an overhang.
- In a small saucepan, melt the butter over medium heat. Add the chopped nuts. Continue cooking, stirring frequently, until the butter foams, subsides, and brown flecks form at the bottom (about 5-7 minutes). Immediately remove from heat. Strain the nuts out, reserving the brown butter. Let both cool slightly.
- In a large bowl, whisk together flour, granulated sugar, brown sugar, baking soda, cinnamon, nutmeg, and salt.
- In a separate medium bowl, mash the ripe bananas until mostly smooth. Whisk in the eggs and vanilla extract until just combined.
- Whisk the reserved cooled brown butter into the wet mixture. Ensure the butter is not hot enough to cook the eggs.
- Pour the wet mixture into the dry ingredients. Using a spatula, fold gently until just combined. Do not overmix.
- Gently fold in the strained toasted nuts.
- Transfer batter to the prepared loaf pan. Sprinkle the top evenly with coarse sugar, if using.
- Bake for 55–65 minutes, or until a wooden skewer inserted into the centre comes out clean or with a few moist crumbs attached.
- Let the loaf cool in the pan for 10 minutes. Carefully lift it out using the parchment overhang and transfer it to a wire rack to cool completely before slicing.