In a large pot cook onion, and garlic over medium heat until well browned. Stir in diced tomatoes, tomato sauce/spaghetti sauce and cooked ground beef.
Season with sugar, basil, Italian seasoning, salt, pepper, and 2 tablespoons parsley. Simmer, covered, for about 2 hours, stirring occasionally.
Preheat oven to 375 degrees F (190 degrees C).
To assemble, spread 1 1/2 cups of meat sauce in the bottom of a 9x13 inch baking dish. Arrange 6 noodles lengthwise over meat sauce. Spread with one half of the ricotta cheese mixture. Top with a third of mozzarella cheese slices. Spoon 1 1/2 cups meat sauce over mozzarella. Repeat layers, and top with remaining mozzarella and Parmesan cheese. Cover with foil: to prevent sticking, either spray foil with cooking spray, or make sure the foil does not touch the cheese.
Bake in preheated oven for 25 minutes. Remove foil, and bake an additional 25 minutes. Cool for 15 minutes before serving.