Preheat oven to 350F. Line a 12-cup muffin tin with wrappers and set aside.
In a large bowl, whisk sugar, vegetable oil, eggs, yogurt, milk, and vanilla until smooth. In a separate bowl, combine flour, cocoa powder, baking powder, and salt.
Fold flour mixture into liquid mixture until just combined. Fold in chocolate chips and zucchini.
Fill muffin cups to brim with batter. Bake muffins at 350F 20-25 minutes until a toothpick inserted in the center of a muffin comes out clean.
Cool muffins completely in pan on a wire cooling rack before serving. Enjoy!
Notes
Store muffins in an airtight container at room temperature up to 3 days. Muffins may be frozen up to 1 month.