Preheat your oven to 375°F (190°C).
In a large skillet, cook the ground beef over medium heat until browned, breaking it up with a spoon as it cooks.
Add the chopped onion and minced garlic to the skillet and cook until softened, about 5 minutes.
Stir in the crushed tomatoes, tomato paste, dried oregano, and dried basil. Season with salt and pepper to taste. Let the sauce simmer for 10-15 minutes, allowing the flavors to meld together.
In a separate bowl, combine the ricotta cheese and egg until well mixed.
To assemble the lasagna, spread a thin layer of the meat sauce in the bottom of a 9x13-inch baking dish. Arrange a layer of cooked lasagna noodles on top, followed by a layer of the ricotta mixture and a sprinkle of mozzarella cheese. Repeat the layers until all ingredients are used up, finishing with a layer of meat sauce on top.
Sprinkle the grated Parmesan cheese evenly over the top of the lasagna.
Cover the baking dish with aluminum foil and bake in the preheated oven for 30 minutes.
Remove the foil and continue baking for an additional 15 minutes, or until the cheese is bubbly and golden brown.
Let the lasagna cool for a few minutes before slicing and serving. Garnish with fresh basil leaves if desired.