Preheat your oven to 350°F (175°C) and grease an 8.5-by-4.5-inch loaf pan with nonstick cooking spray. Consider lining the bottom with parchment paper.

In a light-colored sauté pan, melt 1 stick of unsalted butter over medium heat until it begins to foam. Swirl the pan occasionally until the butter turns golden brown and emits a nutty aroma, about 5–7 minutes. Remove from heat and let it cool slightly.

In a medium mixing bowl, mash 3 large ripe bananas until mostly smooth. Add 3 large room-temperature eggs to the mashed bananas and mix thoroughly until fully incorporated.

In a separate bowl, whisk together 2 cups of all-purpose flour, 1 cup of dark brown sugar, 2 teaspoons of baking powder, 1 teaspoon of ground cinnamon, 1 teaspoon of kosher salt, and 1/2 teaspoon of ground nutmeg. Break up any clumps of brown sugar as you combine.

Pour the banana and egg mixture into the bowl with your dry ingredients. Drizzle in the cooled brown butter. Gently fold the ingredients together until just combined.

Pour the thick batter into your prepared loaf pan, spreading it evenly. Place the halved banana cut-side up on top of the batter. Sprinkle additional brown sugar over the top.

Place the loaf pan in the preheated oven and bake for 70–80 minutes until a toothpick inserted in the center comes out clean.

Let the banana bread cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.