Preheat the oven to 175°C (350°F). Grease and flour your baking pan or line it with baking paper. In a medium bowl, mash the bananas until smooth.
Add the eggs one at a time, beating well after each addition.
Add the baking soda, butter, granulated sugar, brown sugar, flour, baking powder, salt, and cinnamon (if using). Stir until well combined. If using, fold in chopped nuts.
Pour the batter into your prepared pan(s). Bake for 35-40 minutes in a rectangular pan or 25-30 minutes in round pans. The cake is done when a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 10 minutes, then transfer to a wire rack to cool completely. Frost if desired and enjoy!
