- Cook sausage, ground beef, onion, and garlic over medium heat until well browned. Stir in crushed tomatoes, tomato paste, tomato sauce, and water. Season with sugar, and 1 tablespoon salt, pepper, . Simmer, covered, for about 1 1/2 hours, stirring occasionally.
- Bring a large pot of lightly salted water to a boil. Cook lasagna noodles in boiling water for 8 to 10 minutes. Drain noodles, and rinse with cold water. In a mixing bowl, combine ricotta cheese with egg, and 1/2 teaspoon salt.
- Preheat oven to 375 degrees F (190 degrees C).
- To assemble, spread 1 1/2 cups of meat sauce in the bottom of a 9x13 inch baking dish. Arrange 6 noodles lengthwise over meat sauce. Spread with one half of the ricotta cheese mixture. Top with a third of mozzarella cheese slices. Spoon 1 1/2 cups meat sauce over mozzarella, and sprinkle with 1/4 cup Parmesan cheese. Repeat layers, and top with remaining mozzarella and Parmesan cheese. Cover with foil: to prevent sticking, either spray foil with cooking spray, or make sure the foil does not touch the cheese.
- Bake in preheated oven for 25 minutes. Remove foil, and bake an additional 25 minutes. Cool for 15 minutes before serving.