Assemble the lasagna. Scoop a small amount of sauce into the bottom of a 9×13 baking pan. Make a layer of zucchini noodles on the bottom of the pan and then top with more sauce followed by the ricotta filling. Spread the cheese filling across the entire pan then top with some of the mozzarella and another layer of zucchini noodles. Continue layering the lasagna, sauce, cheese filling and mozzarella until the pan is full and you are out of ingredients. End with mozzarella sprinkled on the top of the pan.