Boil 1/2 head of cauliflower until tender. Drain well. Place cauliflower in large bowl, then mash it with a fork until it has the consistency of rice, mix in 1 cup shredded mozzarella cheese and one large egg. Spray a 9×3 bread pan with cooking spray. Pour tomato sauce in bottom of pan (just enough to cover bottom of pan). Layer with 1/2 of cauliflower mixture. Next, layer about 1/4 cup ricotta cheese by dotting small piles and spreading, then a thin layer of tomato sauce. If you want meat, add a layer of either ground beef or ground sausage (or mixture of both!) here. Next layer more mozzarella cheese. Add the rest of cauliflower mix, then a layer of tomato sauce, another layer of meat if you choose, then 1/4 cup ricotta cheese, then top with mozzarella cheese. Bake at 350 for 45 minutes. Let it stand for 10 minutes before serving. Recipe freezes very well so I usually double the recipe and make 2 at a time.