To assemble the lasagnas: Spread 1/3 cup tomato sauce over the bottom of each baking dish. Top each with a layer of 2 lasagna sheets and spread with another 1/3 cup of the sauce. Top each evenly with 2 Tbsp. each ricotta and mozzarella, then scatter over 2 Tbsp. of the spinach and 2 Tbsp. of the sausage. Top each with a layer of zucchini slices, then with 1/3 cup of the sauce and 2 Tbsp. each of the ricotta, mozzarella, spinach, and sausage. Repeat these layers 2 more times (first with the pasta, then with the zucchini). Top each lasagna with 1/4 cup Parmesan. Coat 2 pieces of foil with cooking spray and cover both pans with foil. Label and freeze one lasagna for up to 1 month.