Step 1: In a large skillet or Dutch oven, brown the ground beef and Italian sausage over medium-high heat. Drain excess fat.
Step 2: Add minced garlic and sauté for 1 minute until fragrant. Stir in the marinara sauce and crushed tomatoes. Simmer for 15-20 minutes.
Step 3: In a medium bowl, combine the ricotta cheese, egg, and chopped parsley. Mix well.
Step 4: Preheat your oven to 375°F (190°C).
Step 5: Spread 1 cup of meat sauce on the bottom of a 9x13 inch baking dish. Top with a layer of lasagna noodles.
Step 6: Spread 1/3 of the ricotta mixture over the noodles, followed by 1 cup of meat sauce and 1 cup of mozzarella cheese.
Step 7: Repeat layers (noodles, ricotta, sauce, cheese) twice more. For the final layer, top with remaining noodles, sauce, mozzarella, and Parmesan.
Step 8: Cover with foil (sprayed with non-stick spray) and bake for 25 minutes. Remove foil and bake for another 20-25 minutes until bubbly and golden.
Step 9: Let the lasagna rest for 15 minutes before slicing to ensure the layers stay intact.