First, cook pasta in boiling, salted water (2 tbsp of salt) for 1 gallon of water for 8 minutes. Drain and set aside.
Meanwhile, preheat oven to 375F.
Then, In a bowl large enough to hold pasta plus cheeses and sauce, add ricotta cheese, shredded mozzarella cheese, grated Parmesan cheese, 2 cups of warm tomato sauce, egg, and seasonings.
Next, add drained ziti to cheese mixture and stir until well combined. It will look orange.
Then, in a 13 x 9 x 3"baking dish, spoon 1/4 cup of sauce on the bottom.
Next, add the ziti mixture and spread it out.
Then, place fresh mozzarella cheese slices on top and remaining sauce in between cheese slices.
Last, bake on 375F uncovered for 30 minutes. Let stand 5 minutes before serving. Garnish with fresh parsley or dried.
Make ahead instructions:
Follow recipe instructions except don't bake. You may use a foil pan for make ahead recipe.Cover tightly and freeze up to three months or refrigerate up to 3 days before baking. Bake refrigerated casserole for one hour at 375F covered. Uncover the last 10 minutes so the top can brown a bit.Bake frozen casserole on 375F covered for 1.5-2 hrs. Check the middle to see if it's hot enough. Uncover the last 10 minutes so the top can brown.