In a large pot filled with salted boiling water, cook the lasagna noodles according to the package instructions until al dente. Drain and set aside.
In a large skillet, heat the olive oil over medium heat. Add the diced onion and minced garlic, sauté for about 3 minutes until soft. Add the ground beef, breaking it up as it cooks. Cook until browned; season with salt and pepper. Pour in the marinara sauce, stir well, and let simmer for about 5 minutes.
In a mixing bowl, combine ricotta cheese, 1 cup of mozzarella, ½ cup of Parmesan, egg, and chopped basil. Stir until smooth.
In a 9x13-inch baking dish, spread a thin layer of meat sauce on the bottom. Lay down 3 lasagna noodles. Spread half of the ricotta mixture over the noodles, followed by a third of the meat sauce. Repeat layering: noodles, ricotta mixture, and meat sauce. For the final layer, top with noodles and remaining meat sauce. Sprinkle the rest of the mozzarella and Parmesan on top.
Cover the dish with aluminum foil, lightly sprayed with cooking spray. Bake for 25 minutes. Remove the foil and bake for an additional 15 minutes until the cheese is golden and bubbly.
Let the lasagna cool for about 10-15 minutes before serving.
Notes
Garnish with fresh basil and extra Parmesan before serving.