Cook the lasagna noodles according to the package instructions until al dente. Drain and set aside.
In a large skillet, heat olive oil over medium heat. Add diced onions and minced garlic, sautéing until softened.
Add the ground beef and Italian sausage to the skillet, breaking it apart with a spoon. Cook until browned. Drain excess fat.
Stir in the crushed tomatoes, basil, oregano, salt, and pepper. Bring to a simmer and let cook for about 10 minutes, stirring occasionally.
In a separate bowl, combine ricotta cheese, egg, half of the grated Parmesan, and a pinch of salt and pepper. Mix well until smooth.
To assemble the lasagna, spread a layer of the meat sauce at the bottom of a 9x13 inch baking dish. Place 3 lasagna noodles over the sauce.
Spread a layer of the ricotta mixture over the noodles, followed by a sprinkle of shredded mozzarella. Repeat the layers (meat sauce, noodles, ricotta, mozzarella) until all ingredients are used, finishing with a layer of meat sauce on top.
Sprinkle the remaining mozzarella and Parmesan cheese over the final layer of meat sauce.
Cover the dish with aluminum foil, ensuring it doesn't touch the cheese. Bake in the preheated oven for 25 minutes.
Remove the foil and bake for an additional 15-20 minutes until cheese is bubbly and golden.
Let the lasagna cool for at least 15 minutes before slicing for easier serving.
Notes
Serve slices garnished with fresh basil leaves on top and a side of garlic bread.