Preheat the oven to 350°F with a rack in the middle position. Line a 9x5 inch loaf pan with parchment paper, leaving a 2-inch overhang on the long sides.

In a small saucepan over medium heat, melt the butter. Cook, swirling occasionally, until the foaming subsides, the butter smells nutty, and brown bits form on the bottom. This takes about 5-8 minutes. Watch closely to prevent burning. Immediately pour the brown butter into a large mixing bowl to cool slightly.

In a separate bowl, whisk together the flour, baking soda, baking powder, salt, and cinnamon. Set aside.

Add the brown sugar to the brown butter and whisk vigorously for 1 minute to aerate. Add the mashed bananas and whisk until mostly smooth, with a few small lumps remaining.

Whisk in the eggs, vanilla extract, and optional almond or hazelnut extract until well combined.

Add the dry ingredients to the wet mixture and fold gently with a spatula until just combined. A few streaks of flour are okay; do not overmix.

If using, fold in up to 1 cup of chocolate chips or chopped nuts, reserving a small handful for the top.

Pour the batter into the prepared loaf pan and spread it evenly. Sprinkle the top with coarse sugar. Bake for 55-60 minutes, until a wooden skewer inserted in the center comes out clean and an instant-read thermometer reads about 180°F.

As soon as the loaf comes out of the oven, sprinkle the reserved chocolate chips or nuts on top so they melt slightly from the residual heat.

Let the banana bread cool in the pan on a wire rack for 15 minutes. If needed, run a dull knife along the short ends to loosen. Use the parchment overhangs to lift the loaf out onto a cutting board. Slice into 9 thick pieces and serve warm or at room temperature.