Step 1

Heat olive oil in a large pot over medium heat. Cook and stir sausage in hot oil until slightly brown and crumbly, about 5 minutes. Stir onion in sausage; cook and stir until softened, about 6 minutes.

Step 2

Stir garlic, oregano, and red pepper flakes into onion mixture; cook and stir until fragrant, about 1 minute. Add tomato paste; cook and stir until mixture has a brick-red color, 3 to 4 minutes.

Step 3

Pour chicken stock, diced tomatoes, and bay leaves into pot; bring to a boil, reduce heat to medium-low, and simmer until flavors combine, about 30 minutes. Add rotini to pot and cook until tender yet firm to the bite, about 8 minutes; drain. Stir in basil and season soup with salt and black pepper.

Step 4

Stir ricotta cheese, Parmesan cheese, 1/4 teaspoon salt, and pinch black pepper in a bowl until well-combined.

Step 5

Place a dollop of cheese mixture in the bottom of a soup bowl. Sprinkle some mozzarella cheese over cheese mixture and ladle soup over the top. Repeat with remaining cheese mixture, mozzarella, and soup.