Spread a little sauce on 9 x 13 baking dish. Layer eggplant, sprinkle grated cheese, then shredded cheese, and then spoon sauce over first layer (about half of the jar). Continue to layer until there are four layers (sometimes you need to add more sauce depending on ones own taste). Cover with aluminum foil and place on cookie sheet (to catch overflows).
Cook 2 hours at 350 degrees F. Remove foil and allow to release moisture. Wait for about 30 minutes before cutting into portions