Preheat your oven to 350°F (175°C).
Grease the muffin tin with cooking spray or line it with muffin liners.
In a large mixing bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt.
In another bowl, beat the eggs and add sugar. Whisk until smooth, then stir in milk, avocado oil, and vanilla extract.
Pour the wet ingredients into the dry ingredients and stir gently until just combined.
Fold in the grated zucchini and chocolate chips.
Spoon the batter into the muffin tin, filling each cup about ¾ full.
Bake for 18-20 minutes or until a toothpick comes out clean.
Let the muffins cool in the tin for 5 minutes, then transfer to a wire rack.
