In a large skillet over medium heat, brown the ground beef and sweet Italian sausage, breaking it into pieces with a spatula. After about 8-10 minutes, add the diced onion and minced garlic, cooking until the onion becomes translucent.

Stir in the crushed tomatoes, tomato sauce, and tomato paste, followed by sugar, dried basil, and salt and pepper to taste. Let the meat sauce simmer uncovered for 1.5 hours, stirring occasionally, until the sauce thickens.

While the sauce simmers, bring a large pot of salted water to a boil. Cook the lasagna noodles according to package instructions until al dente. Drain and spread them out on a baking tray to prevent sticking.

In a medium bowl, combine the ricotta cheese, beaten egg, and fresh parsley along with a pinch of salt. Mix until smooth and creamy.

Preheat your oven to 375°F (190°C). In a baking dish, spread a thin layer of meat sauce across the bottom. Begin layering with noodles, followed by half of the ricotta mixture, mozzarella, and Parmesan. Repeat layers, finishing with a layer of sauce and Parmesan.

Cover the baking dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 25 minutes, until the top is golden brown.

Once baked, let the lasagna rest for 15 minutes before slicing.