Place shredded zucchini in a strainer and sprinkle with salt. Let stand 10 minutes. Squeeze thoroughly to press out all the water. (this step is ESSENTIAL)
Combine the squeeze-dried zucchini with eggs, parmesan and half of the cheeses.
Press mixture into a lightly greased baking dish and bake uncovered for 20 minutes.
In the meantime, cook the ground beef and onion (I also salt & pepper the beef and add a bit of lipton onion soup mix for extra flavor) in a medium skillet until done. Drain any grease and excess liquid.
Drain liquid from the can of tomatoes and add to the beef mixture.
Once the zucchini base has finished cooking, add the meat layer and spread evenly to cover the base.
Top the meat mixture with the remaining cheeses. (Optavia suggests topping with chopped bell peppers but I knew my kids wouldn't eat it if they could visibly see the veggies, lol. So I have never included them but this is where you would add them if you were to use them)
Bake for an additional 20 minutes or until cheese has melted.