Preheat the oven to 350 degrees F. Spray two loaf pans with cooking spray, set aside.
In a medium bowl, combine the topping ingredients with your fingers or a spoon. Set aside.
In a large bowl, using an electric hand mixer or wooden spoon, cream together the sugars and butter. Add the mashed bananas, vanilla, eggs and combine well. Add the buttermilk, flour, baking soda, powder and salt and combine well.
Divide the batter evenly between two prepared loaf pans. Spoon topping over each cake, evenly. Bake in the preheated 350 degree F oven for about 50 minutes. Or until a toothpick when inserted comes out clean. Let cool for 20 minutes before removing from the pan. Cut into slices and enjoy.