Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners or lightly grease it.
In a large bowl, combine the shredded zucchini, cooked chicken, and shredded cheddar cheese. Mix well to combine.
In another bowl, whisk together the flour, baking powder, baking soda, salt, black pepper, and garlic powder.
In a separate bowl, beat the eggs, then add the milk and olive oil, mixing until well combined.
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix.
Gently fold in the zucchini, chicken, and cheese mixture until evenly distributed.
Spoon the batter into the prepared muffin tin, filling each cup about 2/3 full.
Bake for 20-25 minutes, or until the muffins are golden brown and a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the tin for 5 minutes before transferring them to a wire rack to cool completely.