Grate the zucchini with box grater. Place the grated zucchini in a paper towel and squeeze out the excess water. Measure 2 cups of zucchini after the water has been removed.
Preheat the oven to 350°F and spray two loaf pans with nonstick spray.
In a large mixing bowl, sift together the flour, salt, baking powder, baking soda, and cinnamon.
In another large mixing bowl, cream together the eggs, vegetable oil, sugar, and vanilla using an electric or stand mixer.
Add the sifted dry ingredients and gently mix to combine.
Fold in 2 cups of zucchini and the chopped walnuts.
Divide the batter evenly between the prepared loaf pans and bake for about 40 to 50 minutes or until a toothpick inserted into the center of each loaf comes out clean.
Allow the loaves to rest in the pans for about 10 minutes before removing from the pans to finish cooling on a wire rack.
Frosting
Use a mixer to combine the butter and cream cheese.
Slowly add the powdered sugar and vanilla and continue mixing until combined.
Spread the frosting over the top of the zucchini bread.
Once frosted, the bread should be stored in the refrigerator.