Brown ground been in large skillet over medium heat until no longer pink, 8-10 minutes. Pour off drippings. Season beef with salt; stir in spaghetti sauce, tomatoes and red pepper; set aside.
2Combine ricotta, spinach, parmesan and egg.
Spread 2 cups beef sauce over bottom of 9x13 baking dish. Arrange 4 uncooked noodles lengthwise in single layer. Place fifth noodle across end of baking dish, breaking noodle to fit dish; press noodles into sauce. Spread entire ricotta cheese mixture over noodles; sprinkle with 1 cup mozzarella and top with 1-1/2 cups beef sauce. Arrange remaining noodles in single layer; press lightly into sauce. Top with remaining beef sauce.
3Bake until noodles are tender about 45 minutes. Sprinkle remaining mozzarella on top; tent lightly with foil. Let stand 15 minutes before serving.