Preheat the oven to 350F. Grease a 9x5" loaf pan and set it aside. After shredding the zucchini, blot it dry with a few paper towels and set it aside.
In a medium bowl, whisk together the melted butter, brown sugar, granulated sugar, egg, yogurt and vanilla until combined. Set aside.
In a seperate large bowl, whisk together the flours, baking powder, baking soda, salt, cinnamon and nutmeg. Add the wet ingredients to the dry and use a rubber spatula to fold it together until just combined. Then fold in the zucchini and the add in of your choice.
Bread: Pour the batter into the prepared loaf pan and sprinkle the rolled oats evenly over the top of the batter. Bake for 40-50 minutes, or until a toothpick inserted into the center comes out clean. Check the bread about halfway through bake time and if the top is browning too quickly, then loosely cover it with foil. Let it cool in the pan on a wire rack until it's cool enough to handle.
Muffins: Scoop the batter into greased or lined muffin tins about 2/3 of the way up and sprinkle the oats over the tops. Bake for 16-18 minutes, or until a toothpick comes out clean. Allow them to cool in the pan for 5 minutes before transfering them to a wire rack to cool completely.
Mini Loaves: Pour the batter into greased mini loaf pans and bake 33-38 minutes, or until a toothpick inserted into the centers comes out clean. Let them cool in the pan on a wire rack until they're cool enough to handle.
