Cook zucchini, covered, in a small amount of boiling water 2 minutes; drain well, and set aside. Combine beef and next 6 ingredients in a skillet. Cook until meat is browned, drain off pan drippings. Add rice and tomato sauce; set aside. Combine egg and cottate cheese; stir well. Layer half of zucchini in a lightly greased 13x9 inch baking dish; top with meat mixture and cottage cheese mixture. Top with remaining zucchini. Cover and bake at 350 for 20 minutes. Add cheddar cheese; bake, uncovered, an additional 5 minutes. Makes 6 servings.