Preheat your oven to 375°F (190°C).
In a large skillet, cook the ground beef or Italian sausage over medium heat until browned and cooked through. Add the chopped onion and minced garlic, and cook until the onion is softened, about 5 minutes.
Stir in the marinara sauce, crushed tomatoes, dried basil, dried oregano, salt, and pepper. Let the sauce simmer for about 10-15 minutes to allow the flavors to meld together.
In a separate bowl, mix together the ricotta cheese, egg, and half of the grated Parmesan cheese until well combined.
To assemble the lasagna, spread a thin layer of the meat sauce on the bottom of a 9x13-inch baking dish. Arrange a layer of lasagna noodles on top of the sauce, followed by a layer of the ricotta mixture and a layer of shredded mozzarella cheese. Repeat the layers until all ingredients are used, ending with a layer of meat sauce on top.
Sprinkle the remaining grated Parmesan cheese over the top of the lasagna.
Cover the baking dish with aluminum foil and bake in the preheated oven for 25-30 minutes. Then, remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden brown.
Remove the lasagna from the oven and let it cool for a few minutes before slicing and serving. Garnish with fresh basil leaves, if desired.