Follow these simple steps to bake a perfect batch of Zucchini Banana Muffins:

1. Preheat and Prepare: Preheat your oven to 350°F (175°C). Line a 12-cup standard muffin tin with paper liners or grease it well with butter or cooking spray. This prevents sticking and makes cleanup a breeze.
2. Prepare the Zucchini: Wash the zucchini thoroughly. Trim off the ends. Grate the zucchini using the medium-sized holes on a box grater. Once grated, place the zucchini in a clean kitchen towel or several layers of paper towels and squeeze out as much excess moisture as possible. This step is crucial to prevent soggy muffins. Set aside.
3. Mash the Bananas: In a small bowl, mash the ripe bananas with a fork until mostly smooth. A few small lumps are perfectly fine and add to the texture. Set aside.
4. Combine Dry Ingredients: In a large mixing bowl, whisk together the all-purpose flour, baking soda, ground cinnamon, ground nutmeg (if using), and salt. Whisking helps to aerate the flour and distribute the leavening agents and spices evenly.
5. Combine Wet Ingredients: In a separate medium mixing bowl, whisk together the large egg and granulated sugar until well combined and slightly pale. Then, whisk in the vegetable oil and vanilla extract until smooth.
6. Add Banana to Wet Ingredients: Stir the mashed bananas into the wet ingredient mixture until just combined.
7. Combine Wet and Dry Ingredients: Pour the wet ingredient mixture into the dry ingredient mixture. Using a spatula, gently fold the ingredients together until just combined. Be careful not to overmix; a few streaks of flour are acceptable at this stage. Overmixing can lead to tough muffins.
8. Fold in Zucchini and Optional Add-ins: Gently fold in the squeezed, shredded zucchini and the chopped nuts or chocolate chips (if using) until they are evenly distributed throughout the batter. Again, avoid overmixing.
9. Fill Muffin Cups: Divide the batter evenly among the 12 prepared muffin cups, filling each cup about two-thirds to three-quarters full. An ice cream scoop works wonderfully for uniform portioning.
10. Bake: Place the muffin tin in the preheated oven. Bake for 20-25 minutes, or until the muffins are golden brown and a wooden skewer or toothpick inserted into the center of a muffin comes out clean or with a few moist crumbs attached.
11. Cool: Once baked, remove the muffin tin from the oven and let the muffins cool in the tin for about 5-10 minutes. This allows them to set slightly. Then, carefully transfer the muffins to a wire rack to cool completely. Cooling them on a wire rack prevents the bottoms from becoming soggy.