Prep your zucchini. Shred 1 cup of zucchini using a box grater, then pile it into a clean kitchen towel or a few layers of paper towels. Twist and squeeze until you've wrung out as much liquid as possible. You should get at least 2 to 3 tablespoons of water out. This step is non-negotiable. Skipping it will flood your batter and ruin the texture.

Preheat your oven to 350°F and grease a 12-cup muffin tin. Use butter, oil, or nonstick spray, and don't skip the sides. These muffins have sugar and chocolate, so they'll stick if you're not generous. If you're using paper liners, spray those too.

Mix your wet ingredients in a large bowl. Whisk together eggs, brown sugar, white sugar, vanilla extract, and melted butter until the mixture is smooth and the sugar starts to dissolve. It should look glossy and slightly thickened.

Combine your dry ingredients in another bowl. Whisk together rolled oats, all-purpose flour, baking powder, baking soda, cinnamon, nutmeg, and salt. Make sure everything is evenly distributed so you don't get pockets of spice or leavening.

Fold the dry into the wet. Add the dry mixture to the wet ingredients and stir gently with a spatula until you see a few streaks of flour left. Don't overmix or your muffins will be tough. This is where tenderness lives or dies.

Add your drained zucchini, chocolate chips, and ground nuts to the batter and fold just until everything is incorporated. The batter will be thick, almost scoopable. That's exactly what you want.

Fill your muffin cups about 3/4 full. Use a spoon or ice cream scoop to divide the batter evenly. These will rise but not overflow if you've measured right.

Bake for about 15- 20 minutes. Start checking for doneness at 15 minutes by inserting a toothpick into the center of a muffin. It should come out clean or with just a few moist crumbs, not wet batter. If you see wet batter, give them another 2 to 3 minutes. Oven temperatures vary.

Cool in the pan for 5 minutes, then move to a wire rack. Let them set up slightly before you try to remove them, or they'll break apart. After 5 minutes, turn them out onto a rack to cool completely. They'll firm up as they cool and the texture will be perfect.