Place 5 bananas into a large microwave save bowl, cover with plastic wrap and then poke three or four holes in the plastic with a knife.
Microwave the bananas in the bowl for 5 minutes so the bananas are soft and release their liquid.
Transfer the bananas to a strainer over a bowl and allow the liquid to drain, stirring occasionally with a spoon for 15 minutes.
While the bananas drain, place the butter into a microwave safe bowl and melt for 1 minute, then let it rest to cool down until needed.
Transfer the banana liquid, 1/2 cup to 3/4 cup, to a medium saucepan and cook on medium-high heat until the liquid is reduced to 1/4 cup, around 5 minutes.
Return the liquid to the bananas in a bowl and stir to combine, then use a potato masher to make sure the bananas are mashed.
By adding the condensed banana liquid back to the bananas, you allow the flavors to become so strong and bold.
To the bananas, whisk in 8 Tbsp butter, 2 eggs, 3/4 cup brown sugar and 1 tsp vanilla, then set aside.
To the bowl of a KitchenAid mixer, add 1 1/4 cup flour, 1 tsp baking soda and 1/2 tsp salt and whisk to combine.
Pour the banana mixture into the KitchenAid bowl with the flour mixture and using the paddle attachment, mix the ingredients together until just combined. Make sure to not over mix the batter.
Preheat the oven to 350 degrees Fahrenheit and spray a 5 X 9-inch loaf pan with non-stick spray, then set aside.
Gently fold the walnuts into the batter if using.
Then, using a spatula, scrape the banana bread mixture into the prepared loaf pan.
Peel and then thinly slice the remaining banana and shingle the banana slices on top of either side of the loaf, leaving a 1 1/2- inch-wide space down the center for the bread to rise.
Sprinkle the top of the Ultimate Banana Bread with the 2 tsp sugar and finally bake the bread for 55-75 minutes or until a knife inserted comes out clean.
Remove the loaf from the oven and let it rest to cool for 15 minutes in the pan before removing to a wire rack to cool completely.
Notes
By adding the condensed banana liquid back to the bananas, you allow the flavors to become so strong and bold.