Preparation: Preheat your oven to 350°F (175°C) and grease a 9-inch round cake pan. Line the bottom with parchment paper for easy removal.
Dry Ingredients: In a mixing bowl, whisk together the flour, granulated sugar, baking powder, baking soda, and salt.
Wet Ingredients: In a separate bowl, using an electric mixer, cream the softened butter until smooth. Add the mashed bananas, eggs, and vanilla extract, and continue mixing until well combined.
Combining the Mixtures: Gradually add the dry ingredients to the wet ingredients, alternating with buttermilk. Begin and end with the dry mixture, and mix until the batter is smooth and well incorporated.
Baking: Pour the batter into the prepared cake pan. Smooth the top with a spatula. Place the prepared batter in the preheated oven and bake for approximately 30 to 35 minutes, or until a toothpick inserted into the center comes clean and free of any batter residue.
Cooling and Frosting: Allow the cake to cool in the pan for 10 minutes before transferring it to a cooling rack to cool completely. Meanwhile, prepare the frosting. Combine the softened cream cheese, softened butter, powdered sugar, and vanilla extract in a bowl. Beat the ingredients together until you achieve a creamy and smooth consistency.
Assembly: Once the cake has cooled, frost the top and sides with the cream cheese frosting. Decorate with sliced bananas on top.