Position a rack in the center of the oven and preheat to 425°F (218°C). Line every other well of two 12-well muffin pans with cupcake liners (leave an empty well between each lined well).

In a medium bowl, whisk together the 1 ¾cups1:1 gluten free flour (260 grams), 2 teaspoons cinnamon, 1 teaspoon baking powder, ½ teaspoon baking soda, ½ teaspoon salt, and ¼ teaspoon ground nutmeg. Set this dry mixture aside.

In a large mixing bowl, combine ½ cup maple syrup, ¼ cup avocado or vegetable oil, ¼ cup applesauce, ¼ cup granulated sugar, 2 large eggs, and 2 teaspoons vanilla extract. Use a hand mixer on medium speed to mix until the wet ingredients are fully combined.

Reduce the mixer speed to low and add 1 cup finely grated zucchini (no need to squeeze out the liquid). Mix just until the zucchini is evenly distributed.

With the mixer still on low, add the reserved dry mixture to the wet mixture. Mix on low speed only until the batter is just combined—do not overmix.

Cover the bowl with plastic wrap and let the batter rest for 20 minutes to allow the gluten-free flour to absorb liquid.

After resting, gently fold into the batter ½ cup of the chocolate chips and ¼ chopped toasted walnuts.

Spoon the batter evenly into the prepared liners, filling each about 2/3 to 3/4 full. Sprinkle the remaining chocolate chips (about ¼ cup) on top of the filled muffins and, if desired, lightly sprinkle sanding sugar over the tops.

Bake at 425°F for 5 minutes. Without removing the pans from the oven, reduce the oven temperature to 350°F and continue baking for an additional 14–17 minutes, or until a toothpick inserted into the center of a muffin comes out clean or with a few moist crumbs.

Remove the pans from the oven and let the muffins cool in the pans for 5 minutes. Then transfer the muffins to a cooling rack to cool completely.