Step 1

Preheat the oven to 425°F and grease a muffin tin.

Step 2

Stir together flour, sugar, baking powder, cinnamon, nutmeg, and salt in a large mixing bowl.

Step 3

In a medium bowl or liquid measuring cup, whisk together yogurt, oil, milk, vanilla, and egg. Stir in zucchini.

Step 4

Pour the wet ingredients into the dry ingredients, stirring with a wooden spoon just until combined. The mixture will be thick. Gently fold in chocolate chips and walnuts, being careful not to over-mix the batter.

Step 5

Spoon batter evenly into 12 muffin cups. Sprinkle each muffin with 1/4 tsp of sugar for a crunchy exterior, if desired. Top with additional chocolate chips. Bake for 8 minutes at 425°F and then reduce the heat to 350°F (keeping muffins in oven) and bake for another 13-14 minutes, or until a knife comes out clean. Cool muffins in tin for 15 minutes before transferring to a wire rack to cool completely.