In a large skillet, heat over medium heat and brown the ground beef and Italian sausage along with the diced onion for about 5-7 minutes until the meats are no longer pink. Drain excess grease, then stir in minced garlic cloves, sautéing until fragrant (about 1 minute). Add marinara sauce, crushed tomatoes, Italian seasoning, salt, pepper, and optional sugar. Simmer gently for 10-15 minutes until thickened.

In a mixing bowl, combine ricotta cheese, softened cream cheese, grated Parmesan, egg, and chopped fresh parsley. Mix until smooth and creamy, which takes about 2-3 minutes of vigorous stirring. Finally, fold in shredded mozzarella cheese to enhance the richness of your creamy filling.

Set your oven to preheat at 375°F (190°C). While it warms up, grab a 9x13 inch baking dish, lightly grease the bottom and sides with cooking spray or a small amount of olive oil.

Start layering your Million Dollar Lasagna by spreading a thin layer of the meat sauce on the bottom of the prepared baking dish. Place down 4 cooked lasagna noodles over the sauce, followed by half of the cheese mixture, another layer of meat sauce, and a sprinkle of shredded mozzarella. Repeat this process until all ingredients are used, finishing with a top layer of meat sauce and remaining mozzarella cheese.

Cover the assembled lasagna with aluminum foil, ensuring it's not touching the cheese. Bake in the preheated oven for 25 minutes. After this time, remove the foil and bake for an additional 15-20 minutes until the cheese is bubbly and turns a golden brown.

Once baked, remove from the oven and let it rest for 10-15 minutes; this allows the layers to set and makes slicing easier. Add a sprinkle of extra parsley on top for color before serving.