Preheat oven to 400°F/200°C/Gas 6. Line a baking sheet with parchment paper and set it aside. According to the package directions, cook the lasagna noodles to just al dente in salted boiling water.

Meanwhile, place the ricotta, half cup of grated mozzarella, Parmesan, egg, and parsley into a medium mixing bowl. Set it aside. Remove as much moisture from the spinach as possible by squeezing it in a cheesecloth or between paper towels. Break up the spinach with your hands or a fork, and add it to the bowl of ricotta mixture. Season to taste with salt and pepper and mix well.

Spread 1 cup of marinara sauce over the bottom of a large casserole dish and set it aside.

Drain and lay the cooked lasagna noodles in a single layer on the prepared baking sheet. Spread each one with 2-3 tablespoons of the ricotta mixture, covering the entire length of the noodle, and roll them up.

Place the rolled-up lasagna into the prepared casserole dish standing upright so you can see the rolled layers on top. Cover the noodles with the remaining marinara sauce and sprinkle on the reserved mozzarella cheese.

Cover the casserole dish with a piece of aluminum foil and bake for 20 minutes. Uncover and bake for another 10 minutes. Allow to cool for 10 minutes before serving. Enjoy!