Preheat oven to 180°C (160°C fan-forced). Spray a 12-cup muffin tin with cooking spray.
In a bowl, combine the flour, brown sugar and cinnamon.
In a separate bowl, mix the eggs, oil, vanilla, apple, banana and zucchini.
Pour the wet ingredients into the dry ingredients and use a spatula to turn the mixture until all ingredients are just moist.
Spoon mixture evenly into muffin tin and bake for 20-25 minutes.