Brown. Cook 1 pound sausage and 3/4 pound beef 8 to 10 minutes until browned and no pink remains; drain the fat. Add aromatics. Cook 1/2 cup onion 4 to 5 minutes, then 2 crushed garlic cloves 30 seconds.
Combine. Stir in 28 ounces tomatoes, 12 ounces paste, 13 ounces sauce, 2 tablespoons sugar, 1 1/2 teaspoons basil, 1/2 teaspoon fennel, 1 teaspoon Italian seasoning, 1/2 teaspoon salt, 1/4 teaspoon pepper, and 2 tablespoons of the 4 tablespoons parsley. Simmer. Partly cover and simmer on low 90 minutes, stirring every 15 minutes.
Prep. Boil and drain 12 noodles; stir 16 ounces ricotta, 1 egg, and the remaining 2 tablespoons parsley together.
Assemble. Set the oven to 375 degrees F. Spread 1 1/2 cups sauce in a 9x13 dish and build two layers of noodles, ricotta, 12 ounces mozzarella, sauce, and 3/4 cup Parmesan, finishing with sauce, mozzarella, and Parmesan.
Bake. Cover and bake 25 minutes, then uncover and bake 25 minutes until bubbling and 165 degrees F in the center.
Rest. Let stand 10 minutes before cutting.