Preheat oven: Heat to 375°F (190°C).
Cook sausage: In a large oven-safe skillet or Dutch oven, heat olive oil over medium heat. Add sausage and cook until browned, breaking it into crumbles. Add garlic and cook 1 minute more.
Add pasta & sauce: Stir in uncooked ziti, marinara sauce, water or broth, Italian seasoning, salt, and pepper. Mix well to coat pasta.
Simmer: Cover and cook over medium heat for 10–12 minutes, stirring occasionally, until pasta starts to soften.
Add cheeses: Dollop ricotta over pasta. Sprinkle mozzarella and Parmesan evenly on top.
Bake: Transfer skillet to oven and bake uncovered for 15–20 minutes until pasta is tender and cheese is melted and bubbly.
Serve: Garnish with fresh basil or parsley before serving.