01 - Preheat oven to 350°F (175°C). Grease and flour a 9×5 inch loaf pan.
02 - In a large bowl, whisk together flour, baking soda, baking powder, and salt.
03 - In a separate bowl, combine melted butter, sugar, eggs, and vanilla extract. Mix well.
04 - Add mashed bananas and drained crushed pineapple to the wet ingredients. Stir until combined.
05 - Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
06 - Fold in the chopped macadamia nuts.
07 - Pour batter into the prepared loaf pan and bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean.
08 - Let cool in the pan for 10 minutes before transferring to a wire rack to cool completely.
09 - Slice and serve.