In a mixing bowl, combine ricotta cheese, egg, half of the shredded mozzarella, half of the grated Parmesan, and Italian seasoning. Stir until smooth.

In a large skillet, heat olive oil over medium heat. Add chopped onion and sauté for about 10 minutes, until soft and translucent.

Include ground beef and ground Italian sausage, cooking until browned. Add minced garlic and cook for 1 more minute.

Stir in chicken broth, marinara sauce, and tomato paste; let simmer for 15 minutes.

Preheat oven to 375°F (190°C).

Bring a pot of salted water to a boil, then add lasagna noodles. Cook until al dente, about 8-10 minutes.

In a casserole dish, spread a thin layer of meat sauce on the bottom. Layer noodles, cheese mixture, more sauce, and repeat, finishing with meat sauce.

Cover with remaining mozzarella and Parmesan cheese. Bake covered with greased aluminum foil for 35 minutes.

Remove foil & bake for an additional 10 minutes until cheese is golden. Let rest for 15 minutes before serving.