In a large saucepan, bring 1/2 inches of water to a boil. Add spinach; cover and boil for 3-4 minutes or until wilted. Drain and squeeze dry.
In a large bowl, combine 3/4 cup cheddar cheese, carrots, bread, eggs, zucchini, 1/4 cup tomato sauce, Parmesan cheese, onion, flaxseed, walnuts, oil, garlic, seasonings and spinach. Pat into a greased 8-in. x 4-in. loaf pan; top with remaining tomato sauce.
Bake, uncovered, at 325° for 45 minutes. Sprinkle with remaining cheddar cheese. Bake 4-7 minutes longer or until heated through and cheese is melted. Let stand for 5 minutes before slicing.