Preheat your oven to 375°F (190°C).
In a large pot of boiling salted water, add the lasagna noodles and cook until al dente, about 8-10 minutes. Drain and set aside.
In a large skillet, heat the olive oil over medium heat. Add the ground beef or Italian sausage, breaking it up with a spoon. Cook until browned, about 5-7 minutes. Drain excess fat if necessary.
Pour in the tomato pasta sauce to the skillet with the cooked meat. Stir to combine and let it simmer for about 5 minutes. Season with salt and pepper to taste.
In a mixing bowl, combine the ricotta cheese, egg (if using), and a pinch of salt and pepper. Mix until smooth and well combined.
In your baking dish, spread a thin layer of the meat sauce at the bottom. Place a layer of lasagna noodles over the sauce, followed by half of the ricotta mixture, one-third of the mozzarella cheese, and a layer of meat sauce. Repeat, finishing with a final layer of noodles and meat sauce. Top with remaining mozzarella and sprinkle Parmesan cheese over the top.
Cover the baking dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden brown.
Once baked, let the lasagna rest for about 15-20 minutes before slicing.
