• Preheat your oven to 350°F (175°C). Grease and flour three 8-inch round cake pans.
• In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
• In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.
• Beat in the eggs, one at a time, followed by the vanilla extract.
• Stir in the mashed bananas until well combined.
• Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk, beginning and ending with the dry ingredients. Mix until just combined.
• Divide the batter evenly among the prepared cake pans and smooth the tops with a spatula.
• Bake in the preheated oven for 20-25 minutes, or until a toothpick inserted into the center of the cakes comes out clean.
• Allow the cakes to cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.

For the caramel frosting:

• In a large mixing bowl, beat the softened butter until creamy.
• Gradually add the powdered sugar, beating well after each addition.
• Add the caramel sauce and vanilla extract, and beat until smooth and creamy.
• If the frosting is too thick, gradually add heavy cream, one tablespoon at a time, until desired consistency is reached.

Assembly:

• Once the cakes are completely cooled, place one layer on a serving plate or cake stand.
• Spread a layer of caramel frosting over the top of the cake layer.
• Repeat the process with the remaining cake layers and frosting, stacking them on top of each other.
• Use a spatula to create a rustic naked look by lightly spreading the frosting around the sides of the cake, leaving some of the cake layers exposed.
• Drizzle additional caramel sauce over the top of the cake and decorate with sliced bananas and chopped nuts for a beautiful finishing touch.