1. In a large pot, heat the oil over medium heat. Add the sausage and saute, breaking it up into small pieces with a wooden spoon, until the sausage is no longer pink, about 5-7 minutes. Drain any excess fat from the pot. Add the onions and saute until softened, about 6 minutes. Add the garlic, oregano, and red pepper flakes and saute for 1 minute. Add the tomato paste and saute until the paste turns a rusty brown, about 5 minutes. Add the tomatoes with their juice, the broth, and the bay leaves and bring the soup to a boil. Reduce the heat and simmer for about 30 minutes.
2. Add the pasta, then increase the heat to medium-high and boil the soup until the pasta is tender to the bite, following the time recommendations on the pasta package. Discard the bay leaves, and then stir in the basil. If desired, season with salt and black pepper to taste.
3. In a small bowl, combine the ricotta, the parmesan, the 1/4 teaspoon salt, and the pinch of pepper. To serve, place about 1 1/2 teaspoons of the ricotta mixture in each bowl, sprinkle with some of the mozzarella and ladle the soup on top.