Begin by boiling a large pot of salted water, then cook the lasagna noodles according to the package instructions until al dente, about 8-10 minutes. Drain the noodles and toss with 2 tablespoons of olive oil to prevent sticking, and set aside to cool slightly.

In a large skillet over medium heat, add 2 tablespoons of olive oil and sauté 1 cup of finely chopped onion and 2 tablespoons of minced garlic until soft and fragrant, about 3-5 minutes. Next, add 1 pound of ground beef, cooking until browned and fully cooked. Drain any excess fat, then stir in 3 cups of tomato sauce, 2 tablespoons of tomato paste, 1 teaspoon of salt, and ¼ cup of chopped fresh parsley. Let this simmer for about 15 minutes.

In a mixing bowl, combine 2 cups of ricotta cheese, ¾ cup of the shredded mozzarella, ¼ cup of the grated Parmesan, 1 beaten egg, and the remaining parsley. Mix thoroughly until smooth and creamy.

Preheat your oven to 375°F (190°C). In a greased 9x13 inch baking dish, spread a thin layer of the meat sauce on the bottom. Place a layer of lasagna noodles over the sauce, followed by a layer of the cheese mixture, then more meat sauce. Repeat the layers until all ingredients are used, finishing with a layer of sauce topped with the remaining mozzarella and Parmesan.

Cover the lasagna with aluminum foil and bake in the preheated oven for 25 minutes. Remove the foil and continue baking for an additional 15-20 minutes, until the cheese is melted, bubbly, and slightly golden on top.

Once baked, remove the lasagna from the oven and allow it to rest for 10-15 minutes before slicing. This resting period helps the layers set, making it easier to serve.