Step 1: In a large pot, brown the ground beef and Italian sausage over medium heat until cooked through. Drain any excess fat.
Step 2: Add the chopped onion and garlic to the meat. Sauté for 5 minutes until the onion is soft and fragrant.
Step 3: Stir in the crushed tomatoes, tomato paste, oregano, and half of the parsley. Season with salt and pepper. Simmer on low heat for 45 minutes to develop the flavor for the lasagna recipe.
Step 4: While the sauce simmers, preheat your oven to 375°F (190°C).
Step 5: In a medium bowl, combine the ricotta cheese, egg, and the remaining parsley. Mix well until smooth.
Step 6: To assemble the lasagna recipe, spread 1 cup of meat sauce in the bottom of a 9x13 inch baking dish.
Step 7: Layer with 3-4 lasagna noodles. Spread 1/3 of the ricotta mixture over the noodles, followed by 1 cup of mozzarella cheese and another cup of meat sauce.
Step 8: Repeat the layers twice more, ending with a final layer of noodles, the remaining meat sauce, mozzarella, and the Parmesan cheese.
Step 9: Cover with foil (ensuring it doesn't touch the cheese) and bake for 25 minutes. Remove the foil and bake for an additional 25 minutes until the cheese is bubbly and golden brown.
Step 10: Let the lasagna recipe rest for 20 minutes before slicing and serving.