In a large skillet, brown beef, onion and garlic. Stir in sauce, tomatoes and seasoning mix. Spoon about half of meat mixture into bottom of 11x7-inch baking dish. In medium bowl, mix cottage cheese, 1 cup cheddar and egg; stuff into shells. Arrange in baking dish. Spoon remaining meat mixture over top.
Cover. Bake 30 minutes. Uncover; bake 10 minutes longer. Sprinkle remaining cheese on top during last 2 minutes. Let stand 10 minutes before serving. Refrigerate leftovers.