Preheat your oven to 350°F (175°C) and prepare a 12-cup muffin pan with paper liners or grease lightly.

In a large mixing bowl, mash the ripe bananas with a fork until mostly smooth, leaving a few small chunks.

Grate the zucchini into a bowl and squeeze out excess moisture. Mix the grated zucchini with the mashed bananas.

Whisk in the eggs, neutral oil, Greek yogurt, and vanilla extract until well combined and creamy.

In a separate bowl, combine the all-purpose flour, baking soda, baking powder, salt, cinnamon, and nutmeg. Whisk together.

Gently fold the dry ingredients into the wet mixture until no dry streaks remain, avoiding overmixing.

Spoon the batter into the muffin cups, filling each about 3/4 full.

Bake for 16 to 20 minutes, or until golden brown and a toothpick inserted comes out clean.

Cool in the pan for 5 minutes before transferring to a wire rack to cool for an additional 10 minutes.