Preheat your oven to 350 degrees Fahrenheit. Grease a 9 by 13 inch baking dish and set aside.
Bring a large pot of water to a roaring boil and cook the ziti according to package directions. Be sure to err on the side of quicker cooking time since this will also bake in the oven. (Continue to Step Three while the water is coming to a boil.)
1 pound ziti
In a large skillet over medium heat, cook the Italian sausage, breaking it up. Cook until it is browned. Then drain the grease from the pan.
1 pound Italian sausage
In the prepared baking dish, combine the cooked ziti, Italian sausage, ricotta cheese, marinara sauce, and 1 1/2 cups of mozzarella cheese. Top the dish with the remaining mozzarella cheese.
28 ounces marinara sauce, 15 ounces ricotta cheese, 3 cups shredded mozzarella cheese
Bake for 30 minutes or until the cheese is melted, bubbly, and beginning to brown. If desired, turn the broiler on for a minute or two to crisp up the top, watching closely so it doesn't burn.