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.

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.

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.