From Yummly, with modifications

½ lb lasagna
1 t salt
1 egg
1 c cooked chopped spinach (packed, water squeezed out; frozen OK)
15 oz part-skim ricotta
2 T minced parsley
½ t salt
¼ t black pepper
3-4 c marinara sauce
4 c shredded mozzarella
1 c grated Pecorino Romano

Preheat oven to 375°. Fill stock pot with water, add salt, and bring to rapid boil. Cook lasagna noodles until al dente, per package. Drain and set aside.

Beat egg in large mixing bowl. Stir in spinach, ricotta, parsley, salt and pepper.

Spoon 1 c sauce into a 13×9″ glass baking dish, spreading evenly. Add a single layer of noodles. Top with ⅓ of the ricotta mixture, 1 c mozzarella, and ¼ c Pecorino. Repeat layers 2 more times, [sauce, noodle, ricotta, mozzarella, Pecorino]. Add final layer of sauce, mozzarella , and Pecorino.

Cover dish with foil and bake for 25 minutes. Remove foil; bake uncovered an additional 25 minutes. Rest for 15 m. before serving.