Step 1: In a large pot, brown the ground beef and Italian sausage over medium heat. Drain excess fat.
Step 2: Add the onions and garlic to the meat and sauté until softened.
Step 3: Stir in the crushed tomatoes, tomato paste, oregano, salt, and pepper. Simmer the sauce for 45 minutes.
Step 4: In a medium bowl, combine the ricotta cheese, egg, parsley, and half of the Parmesan cheese.
Step 5: Preheat your oven to 375°F (190°C).
Step 6: Spread 1 cup of meat sauce in the bottom of a 9x13 inch baking dish.
Step 7: Layer 3-4 noodles over the sauce, followed by a portion of the ricotta mixture and mozzarella cheese.
Step 8: Repeat the layers until all ingredients are used, finishing with a generous layer of mozzarella and the remaining Parmesan.
Step 9: Cover with foil and bake for 25 minutes. Remove foil and bake for an additional 25 minutes until bubbly and golden.
Step 10: Let the lasagna rest for 15 minutes before serving to allow the layers to set.