Preheat the oven to 375°F (190ºC).

In a large dutch oven, bring water to a boil. Add 1 tablespoon of salt and stir to dissolve. Cook the ziti until al dente, about 9 to 10 minutes. Drain and rinse with cool water.

Heat olive oil in the dutch oven over medium heat. Add sausage and cook until browned, about 4 to 5 minutes.

Add onion, garlic, and 1 teaspoon Italian seasoning. Sauté until onions are translucent, about 3 minutes.

Add tomato paste, cook for 1 minute. Add crushed tomatoes, diced tomatoes, 1 teaspoon salt, and ¼ teaspoon black pepper. Simmer for 10 minutes.

Add the ziti to the meat sauce and stir to combine.

In a medium bowl, combine ricotta cheese, 1 cup mozzarella cheese, ¼ cup parmesan cheese, 1 teaspoon Italian seasoning, 1 teaspoon salt, ¼ teaspoon pepper, parsley, and egg.

In a 9x13 baking dish, layer half of the pasta, half of the ricotta mixture, and half of the meat sauce. Repeat layers. Top with remaining mozzarella and parmesan cheese.

Cover with greased foil and bake for 30 minutes. Remove foil and bake until cheese is melted and golden, about 15 minutes.

Garnish with chopped parsley and parmesan cheese if desired.