Cook the lasagna noodles according to package instructions until al dente. Drain and set aside.
In a large skillet over medium heat, combine the ground beef and Italian sausage. Cook until browned. Drain excess fat.
Stir in the chopped onion and minced garlic to the meat mixture. Cook until the onion is translucent (about 3-5 minutes).
Mix in the crushed tomatoes, tomato paste, oregano, basil, salt, and pepper. Bring the sauce to a simmer and let it cook for about 20 minutes, stirring occasionally.
In a bowl, mix together ricotta cheese, egg, salt, and pepper until well combined.
In a 9x13 inch baking dish, spread a thin layer of the meat sauce on the bottom. Place 4 lasagna noodles on top, spread 1/2 of the ricotta mixture over the noodles, followed by 1/3 of the meat sauce and a sprinkle of mozzarella cheese. Repeat the layers once more. Top with the final lasagna noodles, the remaining meat sauce, mozzarella cheese, and sprinkle with Parmesan cheese.
Preheat the oven to 375°F (190°C). Cover the lasagna with aluminum foil (to prevent sticking, spray the foil with cooking spray) and bake for 25 minutes. Remove the foil and bake for an additional 25 minutes until cheese is bubbly and golden.
Let the lasagna cool for 10-15 minutes before slicing to allow the layers to set. Garnish with fresh basil leaves before serving.
Notes
Let the lasagna cool for a few minutes before slicing for better layering.