Making these veggie-packed muffins requires minimal effort but delivers maximum results.
Get Ready: Preheat your oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners or grease it lightly with oil or cooking spray.
Mix Dry Stuff: In a large bowl, whisk together the whole wheat flour, baking soda, baking powder, cinnamon, nutmeg (if using), and salt. Whisking thoroughly helps everything mix evenly.
Mix Wet Stuff: In a separate medium bowl, whisk the eggs. Then whisk in the honey or maple syrup, oil, milk, Greek yogurt, and vanilla extract until smooth.
Add Veggies: Gently fold the grated carrots, grated zucchini (make sure you squeezed out the extra water!), and chopped spinach (if using) into the wet mixture.
Combine: Pour the wet mixture into the bowl with the dry ingredients.
Mix Gently: Stir everything together with a spatula or wooden spoon just until combined. Don't overmix! The batter will look a little lumpy, and that's okay. Overmixing can make muffins tough.
Fill Cups: Divide the batter evenly among the prepared muffin cups, filling each about two-thirds full.
Bake: Bake for 18-22 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Cool: Let the muffins cool in the tin for a few minutes before moving them to a wire rack to cool completely.