Bring a large pot of salted water to a boil. Add the lasagna noodles and cook until al dente, about 8 minutes. Drain and set aside.

In a skillet over medium heat, cook ground beef and Italian sausage until browned, about 5-7 minutes.

Add chopped onion and minced garlic to the skillet and cook until softened, about 3 minutes.

Stir in crushed tomatoes, tomato paste, dried oregano, dried basil, salt, and pepper. Simmer the sauce for 20 minutes, stirring occasionally.

In a mixing bowl, combine ricotta cheese, egg, grated Parmesan cheese, salt, and pepper until smooth.

Preheat the oven to 375°F (190°C).

Spread a thin layer of meat sauce in the bottom of a 9x13 inch baking dish.

Arrange three cooked noodles over the sauce, spread half of the cheese mixture over the noodles, and top with one-third of the meat sauce.

Repeat the layers with three noodles, remaining cheese mixture, and one-third of the meat sauce. Finish with the remaining three noodles and meat sauce.

Sprinkle shredded mozzarella cheese evenly over the top layer.

Cover the baking dish with aluminum foil and bake in the preheated oven for 25 minutes.

Remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden.

Let the lasagna rest for 10 minutes before slicing and serving.