In a large pot, cook the ground beef and Italian sausage over medium heat until browned. Drain excess fat if necessary.
Add the chopped onion and minced garlic to the skillet, cooking until the onion is translucent, about 5 minutes.
Stir in the crushed tomatoes, tomato sauce, tomato paste, basil, oregano, salt, and pepper. Let simmer for about 15 minutes, stirring occasionally.
While the sauce simmers, cook the lasagna noodles according to package instructions. Drain and set aside.
In a mixing bowl, combine ricotta cheese, the egg, and season with salt and pepper.
Preheat the oven to 375°F (190°C).
Assemble the lasagna starting with a layer of meat sauce at the bottom of the baking dish. Add a layer of noodles, then a layer of the ricotta cheese mixture, followed by a layer of mozzarella cheese. Repeat the layers until all ingredients are used, finishing with a layer of meat sauce topped with mozzarella and Parmesan cheeses.
Cover the baking dish with aluminum foil and bake in the preheated oven for 25 minutes. Remove foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden.
Let the lasagna rest for about 10-15 minutes before slicing and serving.