Preheat oven to 350 F. Cook lasagna noodles according to package directions, drain. Brown ground beef in a large saucepan over medium heat, breaking it up with a spatula as it cooks until it is no longer pink. Drain grease and return beef to skillet.
Add crushed tomatoes, tomato paste, minced garlic, salt, dried oregano and thyme to beef. Let simmer for 20 minutes. In a medium bowl, mix together ricotta cheese, grated parmesan cheese and egg.
Spread a thin layer of meat sauce in the bottom of a large baking dish. Layer with 4 noodles, ricotta cheese mixture, 3/4 cup mozzarella cheese and more meat sauce. Repeat layers 4 times, ending with a layer of 4 lasagna noodles, ricotta cheese mixture, meat sauce and top with remaining 3/4 cup of mozzarella cheese.
Cover with foil and bake for one hour. Uncover and bake for another 15-20 minutes.
