01 - Preheat oven to 350°F. Grease and line a 9-inch square or round cake pan with parchment paper.
02 - In a large mixing bowl, whisk together mashed bananas, eggs, vegetable oil, granulated sugar, light brown sugar, and vanilla extract until completely smooth.
03 - In a separate bowl, whisk together all-purpose flour, baking soda, baking powder, ground cinnamon, and salt until well blended.
04 - Gradually add the dry ingredients to the wet mixture, stirring with a spatula just until combined. Avoid overmixing to ensure a tender crumb.
05 - If desired, gently fold in chopped walnuts or pecans and chocolate chips.
06 - Transfer batter to the prepared pan, spreading evenly and smoothing the surface.
07 - Bake for 35 to 40 minutes, or until a toothpick inserted in the center emerges clean or with a few moist crumbs.
08 - Let the cake cool in the pan for 10 minutes, then transfer to a wire rack to cool fully. Slice and serve warm or at room temperature.