Preheat oven to 375 degrees F. Coat a 9- x 13-inch baking dish with cooking spray and spread 1 cup spaghetti sauce evenly over bottom. Cook lasagna noodles according to package directions; drain well.
Meanwhile, in a large skillet over medium-high heat, cook beef and sausage until no pink remains, stirring to break up meat as it cooks. Drain off excess liquid and add remaining spaghetti sauce to meat; mix well.
In a large bowl, combine ricotta cheese, Parmesan cheese, egg, parsley, garlic powder, and salt; mix well.
Place 3 noodles over sauce. Spread 1/3 of cheese mixture over noodles, layer with 6 slices mozzarella cheese and spoon 1/3 of meat sauce over cheese. Repeat with 2 more layers, ending with meat sauce and cover with foil.
Bake 50 minutes, uncover, and place remaining cheese on top. Return to oven to finish baking for 15 to 20 minutes, or until heated through in center. Allow to sit 10 minutes before serving.