Preheat the oven to 350°F and grease and line a 9×5-inch loaf pan with parchment paper. Make sure the paper fits up the sides so the loaf releases cleanly.

Melt the unsalted butter in a light-colored saucepan over medium heat and cook for 5–7 minutes, stirring frequently. When it turns deep golden brown with a rich nutty aroma, remove from the heat and cool for 10 minutes.

Whisk the browned butter, mashed ripe bananas, large eggs, light brown sugar, granulated sugar, and vanilla extract until smooth. Stop once the mixture looks uniform and glossy.

Combine all-purpose flour, baking soda, baking powder, salt, ground cinnamon, and ground nutmeg in a separate bowl. Whisk just until the spices are evenly distributed.

Fold the dry ingredients into the banana mixture just until combined, then stir in the chopped pecans. Avoid overmixing so the loaf stays tender.

Pour the batter into the prepared loaf pan and smooth the top. Sprinkle with coarse sugar if using.

Bake at 350°F for 55–65 minutes, until a toothpick inserted into the center comes out clean or with a few moist crumbs. Look for a deeply golden loaf with a beautifully cracked top.

Cool in the pan for 15 minutes before transferring to a wire rack. Let the bread cool completely before slicing.