In a medium pot, cook ground beef and onion over medium heat. Continue to cook and crumble beef until no longer pink. Drain any grease.
Add minced garlic and cook for 30 seconds. Pour in diced tomatoes, tomato sauce, paste, oregano, basil, Italian seasoning, sugar, salt and pepper. Stir and bring mixture to a boil. Reduce heat to low and let simmer for 30 minutes.
Meanwhile, boil lasagna noodles in a large pot of water until al dente. Drain water, then lay noodles out on a wax-paper lined baking sheet. (Don't let noodles touch because they will stick.)
Spread 1 cup of sauce on the bottom of a 9x13-inch baking dish. Lay 3 noodles over sauce. Drop a third of the cream cheese, by teaspoonfuls, over the noodles. Sprinkle 1/2 cup Mozzarella and 1/2 cup Parmesan cheese on top, then spoon a third of the sauce on top. Repeat layers two more times, ending with the last of the cheeses. (Sprinkle very top with dried Parsley, if desired.)
Cover with foil. Bake in a preheated 350 degree F. oven for 45 minutes. Carefully remove foil (it will be hot!) then bake another 5 to 10 minutes or until cheese is bubbly and melted. Remove from oven and let stand 10 minutes before slicing and serving. Enjoy!