Prepare the Cake Batter:
Preheat your oven to 350°F (175°C). Grease and line two 9-inch round cake pans with parchment paper.
In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
In a large bowl, cream the butter, granulated sugar, and brown sugar until light and fluffy. Beat in the eggs, one at a time, then mix in the mashed bananas and vanilla extract.
Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk. Begin and end with the dry ingredients. Gently fold in the chopped pecans.
Bake the Cakes:
Divide the batter evenly between the prepared cake pans.
Bake for 25–30 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.
Make the Caramel Frosting:
In a saucepan over medium heat, melt the butter and stir in the brown sugar. Cook for 2–3 minutes, until the sugar dissolves.
Add the heavy cream and bring the mixture to a gentle boil, then remove from heat and stir in the vanilla extract.
Let the mixture cool slightly, then beat in the powdered sugar until smooth and creamy.
Assemble the Cake:
Place one cake layer on a serving plate and spread a generous layer of caramel frosting on top.
Add the second cake layer and frost the top and sides of the cake.
Add Toppings:
Sprinkle chopped pecans over the cake and drizzle with caramel sauce if desired.