One shortcut made this meal simple to make. Instead of preparing the sauce myself, I used a 24 ounce can of Hunts Four Cheese Pasta Sauce.
Warm the pasta sauce in a pan. While the sauce is heating, boil four quarts of water for 2/3 of a box of Ronzoni gluten-free penne pasta (or, if preferred, ziti made of wheat flour). When the water is boiling hard, add the pasta. (If the water threatens to boil over, add a few drops of vegetable oil to the pan.) Cook according to directions on the box. Drain, rinse, and set aside.
Preheat the oven to 375 degrees F.
Spoon a 15 ounce carton of ricotta cheese into a small mixing bowl and add one egg and a tablespoon of chopped parsley. Mix and set aside.
Grate 3/4 pound of mozzarella cheese and set aside.
Grate 1 cup of Parmesan cheese. (Or use a cup from a bag of grated Parmesan cheese. I did.) Set aside.
Choose an 8″ X 8″ baking dish.
With a ladle add enough pasta sauce to cover the bottom of the baking dish (about 1/3 of the sauce). Add a layer of pasta (half of the pasta), then a layer using half the ricotta cheese mixture, and next a layer of grated mozzarella cheese, about one-third of it. Add another layer of pasta sauce, and sprinkle half the grated Parmesan cheese over the top.
Repeat layers, beginning with the rest of the pasta, the remainder of the ricotta cheese, another layer of mozzarella cheese, then the remainder of the sauce, next the more mozzarella, and sprinkle the top with the remainder of the Parmesan cheese.
Dot the top with butter. Spray aluminum foil with cooking oil or rub oil on the surface of the foil so the cheese will not stick. Cover the dish with the foil, and place it in a 375 degree oven for 25 minutes. Remove foil and bake for 25 minutes longer. Cool 15 minutes before serving.