Grate 1 medium sized zucchini (until you have 2 cups). Set aside. Preheat oven to 350 degrees. Lightly grease 8 1/2" x 4 1/2" loaf pan (or spray with cooking spray).
Grab a large mixing bowl, add 3/4 c brown sugar, 2 T apple cider vinegar, 1/2 c canola oil, 2 eggs, and 1 tsp vanilla to bowl. Beat with whisk or hand mixer until smooth.
In a medium mixing bowl, whisk together 1 c whole wheat flour, 3/4 c all purpose flour, 1/4 tsp baking powder, 1/2 baking soda, 1 tsp salt, and 1 1/2 tsp cinnamon.
Whisk dry ingredients into wet ingredients. Add shredded zucchini into batter and fold in with a rubber spatula. Pour batter into greased loaf pan. Smooth top with rubber spatula.
Bake bread for 55-60 minutes, or until a toothpick comes out clean (from the center of the bread). Remove from oven, let cool for about 15 minutes, then turn it over onto a cooling rack to cool completely. Slice when cooled.
Reheat or eat at room temperature. Serve with peanut butter or butter.