Prep your pan and oven: Heat the oven to 350°F (175°C). Line a 12-cup muffin pan with paper liners or grease well to prevent sticking.
Grate the zucchini: Use the fine side of a box grater.
Place the grated zucchini in a clean kitchen towel and lightly squeeze out excess moisture. Don’t wring it dry—just remove the drips so the muffins stay moist.
Mash the bananas: In a large bowl, mash the bananas until mostly smooth with a few small lumps.
Mix the wet ingredients: Whisk in the eggs, oil (or melted butter), vanilla, and maple syrup or honey until well combined. Stir in the grated zucchini.
Combine dry ingredients: In a separate bowl, whisk the flour, baking powder, baking soda, cinnamon, and salt.
Bring it together: Add the dry ingredients to the wet.
Stir with a spatula just until you no longer see dry flour. If using add-ins, fold them in gently. Do not overmix or the muffins can turn dense.
Fill the pan: Divide the batter evenly among the muffin cups, filling each about 3/4 full.
Bake: Bake for 16–20 minutes, or until the tops are set and a toothpick in the center comes out clean or with a few moist crumbs.
Cool: Let the muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely. This helps them set and prevents soggy bottoms.
Serve: For toddlers, cut in half or into quarters if needed.
Serve plain or with a smear of yogurt or nut butter for extra protein.