
Preheat oven to 375°F (190°C). In a large skillet, brown ground beef over medium-high heat. Drain any excess grease.
Add chopped onion and garlic to the skillet and cook until softened, about 5 minutes.
Stir in tomato sauce, tomato paste, Italian seasoning, sugar, salt, and pepper. Bring to a simmer and cook for 15 minutes, stirring occasionally.
In a separate bowl, combine ricotta cheese, egg, Parmesan cheese, and parsley. Mix well.
Spread a thin layer of meat sauce in the bottom of a 9x13 inch baking dish. Layer lasagna noodles, ricotta mixture, mozzarella cheese, and meat sauce. Repeat layers twice more, ending with a layer of meat sauce and mozzarella cheese.
Cover the baking dish with foil and bake for 25 minutes. Remove the foil and bake for an additional 20 minutes, or until the cheese is melted and bubbly.
Let the lasagna rest for 10-15 minutes before slicing and serving.