Heat olive oil in a large skillet over medium high heat. Add Italian sausage and onion and cook until browned, about 10 minutes, making sure to crumble the sausage as it cooks; drain excess fat. Stir in garlic and red pepper flakes.
Stir in crushed tomatoes, oregano, and season with salt and pepper, to taste.
Bring to a simmer and stir in 1/2 cup wine and 1/2 cup water. Add pasta, push it down so that it is under the liquid. Bring to a boil; cover, reduce heat and simmer about 15 minutes. Stir pasta and make sure none is sticking to the bottom. Cover and cook 15-20 more minutes or until pasta is cooked.
Remove from heat. Top with dollops of ricotta, followed by the mozzarella. Cover until heated through, about 2-4 minutes.
Uncover and place under broiler until cheese is brown and bubbly
Serve immediately, garnished with parsley or basil, if desired.
The wine really adds to the flavor of the sauce, but if you don't want to use it, you can use water or broth.