Preheat oven to 350°F (175°C).
Grease a 9x5-inch loaf pan or line it with parchment paper.
In a bowl, whisk together flour, baking soda, salt, and cinnamon. Set aside.
In another bowl, mash the ripe bananas until smooth.
In a large bowl, mix melted butter, granulated sugar, and brown sugar.
Add eggs and vanilla extract, whisking until smooth.
Stir in mashed bananas.
Gradually fold the dry ingredients into the wet mixture until just combined.
Gently stir in chopped walnuts.
Pour batter into the prepared loaf pan.
Bake for 55-60 minutes or until a toothpick inserted comes out clean.
Let cool in the pan for 10 minutes, then transfer to a wire rack.
Slice and enjoy warm or at room temperature.
