Start by heating a large skillet over medium heat. Add the ground beef and chopped onion to the skillet. Cook until the beef is browned and the onion is soft, about 5 to 7 minutes. Drain any excess fat.

Add the spaghetti sauce to the cooked beef and onion. Stir and let it simmer for about 10 minutes on low heat.

In a mixing bowl, combine the ricotta cheese with a little salt and pepper for seasoning. Optionally, add an egg for a creamier consistency.

Bring a pot of salted water to a boil and cook the lasagna noodles according to package instructions until al dente. Drain and lay flat on a clean kitchen towel.

In a large baking dish, spread a thin layer of meat sauce at the bottom. Layer three noodles, half of the ricotta mixture, some mozzarella cheese, and more meat sauce. Repeat until all ingredients are used, finishing with a layer of meat sauce topped with remaining mozzarella and parmesan cheese.