Place the onion, garlic, and olive oil, and fresh rosemary in a 6-quart soup pot or dutch oven. Sautee over medium heat for 5 minutes or until the onions are translucent.

Add in the diced tomatoes, tomato sauce, oregano, basil, salt, pepper, chicken stock, and heavy cream and stir to combine. Simmer for 20 minutes.

Place the three-cheese tortellini into the soup and cook for 12-15 minutes or until the tortellini are tender and cooked through.

Stir in the parmesan cheese.

Serve and garnish with fresh basil and shredded parmesan cheese.