Preheat oven to 350°F (175°C). Lightly grease a 9x5-inch loaf pan or line with parchment paper.

Mash bananas in a large bowl until smooth.

Add wet ingredients: Mix in melted butter, eggs, brown sugar, granulated sugar, and vanilla extract. Whisk until combined.

Add dry ingredients: Stir in flour, baking soda, and salt. Mix gently until just combined.

Fold in nuts: Gently fold in chopped walnuts or pecans.

Pour batter into prepared loaf pan and smooth the top.

Bake for 55–65 minutes, or until a toothpick inserted in the center comes out clean. Cover with foil if the top browns too quickly.

Cool: Let bread cool in the pan for 10–15 minutes, then transfer to a wire rack to cool completely before slicing.