Heat a large pot over medium-high heat then add the ground beef and sausage and cook until browned, about 6 minutes., using a spatula to break apart the meat while it cooks.
Add the diced onion and cook for 3 minutes or until soft and translucent.
Stir in the marinara sauce, tomatoes, garlic, tomato paste, 1 tablespoon of parsley, 1 tablespoon of basil, Italian seasoning and salt. Simmer on low heat for at least 30 minutes or up to 4 hours or until the sauce has reduced slightly, stirring occasionally.
Preheat your oven to 350 degrees Fahrenheit.
Just before assembling the lasagna, add the ricotta cheese, egg, and sugar to a medium bowl and mix well. Next, stir in the remaining parsley and basil, 1 cup of mozzarella cheese, and ¼ cup of parmesan cheese, mix well, and set aside.
To assemble, spread a layer of the meat sauce in a 9x13-inch baking pan. Arrange the lasagna noodles on top of the sauce and spread ⅓ of the ricotta mixture over the noodles. Then, sprinkle ⅓ of the remaining mozzarella and parmesan on top.
Repeat this process until there is a final layer of the cheese mixture with mozzarella and parmesan cheese on top.
Cover the pan with aluminum foil and bake for 45-55 minutes or until the cheese is melted and bubbly.
Optional: Broil the lasagna for 1-2 minutes or until the cheese is lightly golden on top.
Remove the lasagna from the oven and allow to cool for 10-15 minutes before serving. Garnish with freshly minced parsley and fresh basil leaves if desired.