Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with paper liners.
In a large bowl, whisk together the flour, sugar, baking powder, baking soda, and salt.
In another bowl, beat the eggs lightly, then add the crushed pineapple (with juice), vegetable oil, and vanilla extract. Mix well.
Pour the wet ingredients into the dry ingredients and stir just until combined. If using, fold in the shredded coconut and chopped macadamia nuts.
Scoop the batter into the prepared muffin tin, filling each cup about two-thirds full.
Bake for 20-25 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Allow the muffins to cool in the tin for about 5 minutes before transferring them to a wire rack to cool completely.
Variations & Tips
For a fun twist, you can add a teaspoon of ground cinnamon or ginger for a bit of spice. If you’re not a fan of macadamia nuts, you can substitute with chopped walnuts or pecans. Feeling indulgent? Try adding a handful of white chocolate chips to the batter. And for a healthier take, you can replace half of the all-purpose flour with whole wheat flour and reduce the sugar by a third.