01 - Preheat oven to 350°F. Grease and line a 9-inch round or square cake pan with parchment paper.
02 - In a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy, approximately 3-4 minutes.
03 - Add eggs one at a time, beating well after each addition. Mix in mashed bananas, buttermilk, vegetable oil, and vanilla extract until thoroughly combined.
04 - In a separate bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until evenly distributed.
05 - Gradually fold the dry ingredient mixture into the wet ingredients until just combined. Be careful not to overmix, as this will affect the cake's texture.
06 - Pour the batter into the prepared cake pan and smooth the top with a spatula. Sprinkle chopped nuts evenly over the surface if desired.
07 - Bake for 30-35 minutes, or until a toothpick inserted into the center of the cake comes out clean.
08 - Allow the cake to cool in the pan for 10 minutes, then transfer to a wire cooling rack to cool completely.
09 - Once fully cooled, spread cream cheese frosting over the top of the cake if desired, then slice and serve.