Preheat the Oven: Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan or line it with parchment paper for easy removal.
Mix Wet Ingredients: In a large mixing bowl, beat together the softened butter and brown sugar until light and fluffy. Add the eggs, mashed bananas, crushed pineapple, and vanilla extract. Stir until well combined.
Combine Dry Ingredients: In a separate small bowl, whisk together the flour, baking soda, baking powder, salt, and cinnamon (if using).
Mix the Dry into the Wet: Gradually add the dry ingredients to the wet mixture, stirring until just combined. Be careful not to overmix, as this can make the bread dense.
Add Coconut and Milk: Gently fold in the shredded coconut and buttermilk (or regular milk). If you're using nuts, fold them in now.
Pour into Pan: Pour the batter into the prepared loaf pan and spread it evenly.
Bake: Bake for 55–65 minutes, or until a toothpick inserted into the center of the loaf comes out clean. If the top starts to brown too quickly, you can cover it with aluminum foil to prevent over-browning.
Cool: Allow the bread to cool in the pan for 10 minutes, then transfer it to a cooling rack to cool completely.
