Prepare the Oven and Pan: Preheat the oven to 350°F (175°C). Line a loaf pan with parchment paper, then set the prepared pan aside.
Cream the Sugar and Butter: In the bowl of a stand mixer, combine the granulated sugar and melted salted butter. Beat until the mixture is light and fluffy.
Add the Wet Ingredients: Add the mashed bananas, vanilla extract, and eggs to the butter mixture. Mix until everything is fully combined.
Combine the Dry Ingredients: In a separate bowl, whisk together the all-purpose flour, baking soda, baking powder, and ground cinnamon until evenly mixed.
Make the Batter: Gradually add the dry mixture to the wet ingredients, mixing until the ingredients are fully incorporated. Avoid mixing beyond this point.
Fold in the Macadamias: Add the chopped macadamia nuts and gently fold them through the batter until evenly distributed.
Fill the Loaf Pan: Pour the finished batter into the parchment-lined loaf pan and spread it evenly.
Bake the Banana Bread: Place the pan in the preheated 350°F (175°C) oven and bake for 55–65 minutes, or until a toothpick inserted into the loaf comes out clean.
Cool Before Slicing: Allow the banana bread to cool completely in the pan before removing and cutting it into slices.