Cook the ground beef, onion, and garlic in a large skillet over medium heat until the meat is browned and the onion is tender. Drain any excess fat.

Stir in crushed tomatoes, tomato paste, water, and Italian seasoning. Bring the sauce to a simmer, then reduce heat, cover, and let it cook for at least 30 minutes, or longer for richer flavor.

While the sauce simmers, cook lasagna noodles according to package directions. Drain and rinse with cold water to prevent sticking.

In a medium bowl, combine ricotta cheese, egg, and parsley. Season with salt and pepper.

Preheat your oven to 375°F (190°C).

Spread a thin layer of meat sauce on the bottom of a 9x13 inch baking dish. Arrange a single layer of cooked lasagna noodles over the sauce.

Spread half of the ricotta cheese mixture over the noodles, then top with a layer of mozzarella cheese and another layer of meat sauce. Repeat the layers, finishing with noodles, sauce, and a final generous layer of mozzarella cheese.

Cover the baking dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 20-25 minutes, or until the cheese is bubbly and lightly browned.

Let the lasagna rest for 10-15 minutes before slicing and serving to allow the layers to set.