Melt the butter in a large pan over medium-high heat. Gradually add fresh spinach to the pan, allowing each batch to wilt before adding more. Season with salt and pepper to taste as the spinach cooks down. Once all the spinach is wilted, let it cool slightly, then squeeze out any excess water. Coarsely chop the cooked spinach and set aside. I always squeeze the spinach really well—otherwise, your lasagna might turn out watery.

In a large bowl, combine the chopped cooked spinach from Step 1, ricotta cheese, eggs, grated Parmesan, 1 cup of shredded mozzarella, 1/2 teaspoon salt, 1/4 teaspoon pepper, and Italian seasoning. Stir everything together until well mixed and evenly distributed.

Cook the lasagna noodles according to the package directions, usually in a large pot of salted boiling water until al dente. Drain and set aside, laying them flat on a surface or lightly oiled baking sheet so they don't stick together.

Preheat the oven to 375°F and coat a 9"x13" baking pan with cooking spray. Spread a small amount of marinara sauce on the bottom of the pan. Add a layer of cooked lasagna noodles from Step 3, then spread 1/3 of the cheese and spinach mixture from Step 2 over the noodles. Top with 1/3 of the marinara sauce. Repeat the layers until all ingredients are used, ending with a final layer of marinara sauce. I find that spreading the sauce all the way to the edges makes every bite nicely saucy.

Cover the assembled lasagna with foil and bake in the preheated oven for 45 minutes. Then, remove the foil, sprinkle the remaining 2 cups of shredded mozzarella evenly over the top, and bake uncovered for an additional 15 minutes or until the cheese is melted and lightly browned. For a browner top, you can broil it for a minute or two at the end—but watch it closely!

Remove the lasagna from the oven and sprinkle it with chopped parsley for a fresh finish. Let the lasagna stand for 5 to 10 minutes before slicing, which helps the layers set and makes serving easier. Enjoy!