Preheat an oven to 325 degrees F (165 degrees C). Grease 2 8x4-inch loaf pans or 2 12-cup muffin pans.
Place the zucchini in a strainer and set aside to drain into a bowl or sink.
Sift the flour, cinnamon, baking soda, baking powder, and salt together in a large bowl. Create a well in the middle of the flour mixture; combine the applesauce, vanilla, eggs, butter, walnuts, and drained zucchini in the center of the well.
Mix until all ingredients are combined into a batter; pour into the loaf pans.
Bake the loaves in the preheated oven until a toothpick inserted into the center comes out clean, about 1 hour for loaves or 25 minutes for muffins. Cool in the pans for 10 minutes before removing to cool completely on a wire rack.
