01 - Preheat oven to 350°F (175°C). Grease and line a 9-inch square or round cake pan.
02 - In a large mixing bowl, whisk together mashed bananas, eggs, vegetable oil, granulated sugar, light brown sugar, and vanilla extract until the mixture is smooth.
03 - In a separate bowl, whisk together all-purpose flour, baking soda, baking powder, ground cinnamon, and salt.
04 - Add the dry ingredients to the wet ingredients in batches, stirring gently after each addition until just combined. Avoid overmixing.
05 - Fold in chopped walnuts, pecans, or chocolate chips if desired.
06 - Pour the batter evenly into the prepared pan and smooth the surface with a spatula.
07 - Place the pan in the oven and bake for 35 to 40 minutes, or until a toothpick inserted in the center comes out clean.
08 - Allow the cake to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely. Slice and serve warm or at room temperature.