Bring a large pot of water to a boil. Add the tortellini and cook until tender, about 10 minutes.

In a large saucepan, combine the tomatoes, spinach, salt, pepper, basil, and garlic over medium heat. Cook and stir until mixture begins to bubble. Whisk together flour, milk, and cream in a medium bowl and add to vegetable mixture along with Parmesan cheese; heat through. Reduce heat to low and simmer until thick, about two minutes.

Drain tortellini (do not rinse) and add to saucepan with the sauce. Stir to coat and serve immediately.