Prepare pizza sauce- In a large saucepan over medium heat, combine tomato sauce and paste. Add remaining ingredients. Mix well. Bring to a boil, stirring constantly. Reduce heat. Cover and simmer for 1 hour, stirring occasionally.
Place zucchini in colander. Sprinkle with salt. Let stand for 10 minutes. Then squeeze out moisture.
Combine zucchini with eggs, Parmesan cheese, and half the mozzarella and cheddar cheeses.
Press into a greased 13 X 9 dish. Bake 20 minutes.
Meanwhile, in a large saucepan, cook beef and onion over medium heat. Drain.
Add homemade pizza sauce, spooning over zucchini mixture.