Heat olive oil in a large pot over medium heat. Add sausage, breaking up into bite-size pieces and brown for 5-6 minutes. Add onions and cook until softened, about 5-6 minutes. Add garlic, oregano and red pepper flakes. Cook for 1 minute.
Add tomato paste and stir well to incorporate. Add diced tomatoes, bay leaves and chicken stock. Stir to combine all ingredients. Bring to a boil and then reduce heat and simmer for 10 minutes.
Add uncooked pasta and cook until al dente, about 10 minutes.
Meanwhile, prepare the cheesy goodness. In a small bowl, combine the ricotta, salt, pepper, and mozzarella; stir to combine.
Add the basil and pepper to the soup; stir. To serve, place a dollop of the cheesy goodness in each soup bowl and ladle the hot soup over the cheese.