Slice zucchini into 1/4 inch slabs, sprinkle with 1 tsp salt and let sit for at least 30 minutes and up to 1 hour. Preheat oven to 375º F/190º C and prepare two baking sheets with foil and a thin layer of oil. Pick up each zucchini slice and slide your fingers down it to remove the excess water and place them in a single layer on the baking sheets. Bake for 20-30 minutes and let cool for 10 minutes before handling.
While the zucchini slices are cooking and cooling, brown your sausage or mushrooms in a skillet (use a little butter or oil for the mushrooms). If you are using mushrooms, feel free to add a half-teaspoon of fennel, 1-2 cloves of garlic and 1/2 teaspoon crushed red pepper flakes to boost flavor. Break up the sausage and/or mushrooms into very small pieces and make it's well-browned. Remove from heat, drain off excess fat from the sausage and add your tomato sauce.
In a medium-sized mixing bowl, combine ricotta, eggs, 1 1/2 cups of the mozzarella cheese (reserve 1/2 cup for topping), basil, parsley, nutmeg, remaining 1 tsp salt, and pepper.
In a 9×13 pan, place one layer of zucchini slices followed by 1/2 of the ricotta cheese mixture, then 1/2 of the tomato mixture. Repeat and end with a layer of zucchini slices if you have enough. Sprinkle the remaining 1/2 cup of mozzarella cheese and Parmesan cheese over the top, then bake at 375º F/190º C for 45 minutes or until the cheese on top of the lasagna is browning and bubbly. Cool for 15 minutes before serving.