1. Preheat your oven to 350F (175C). Grease and flour a 9-inch round cake pan.
2. In a bowl, whisk together the flour, baking powder, baking soda, and salt.
3. In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until fluffy.
4. Beat in the eggs one at a time, followed by the vanilla extract.
5. Stir in the mashed bananas and sour cream until combined.
6. Gradually fold in the dry ingredients until just mixed. Gently stir in the chopped pecans.
7. Pour the batter into the prepared cake pan and bake for 40-45 minutes, or until a toothpick inserted into the center comes out clean.
8. Allow the cake to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.

For the Caramel Sauce:

1. In a saucepan, heat the sugar over medium heat, stirring constantly until it melts and turns amber-colored.
2. Add the butter and stir until fully melted.
3. Slowly pour in the heavy cream, continuing to stir until the mixture is smooth.
4. Add a pinch of salt and remove from heat. Let the caramel cool for a few minutes.

To Assemble:

• Pour the caramel sauce generously over the cooled cake. Sprinkle extra pecans on top for decoration if desired.