Fill a large pot about three-quarters full with water and bring to a rolling boil.
Stir 1/2 tablespoon salt into the boiling water.
Add the frozen cheese tortellini and cook according to package directions, or until they float and are tender, about 7–10 minutes.
Drain the tortellini in a colander and transfer to a medium bowl.
Add the slow roasted tomatoes and the chopped spinach to the warm tortellini; if tomatoes are frozen, make sure they are defrosted and reheated before adding.
Drizzle with a little olive oil and gently toss until the spinach wilts slightly and everything is combined.
Serve warm and garnish with freshly grated Parmesan cheese to taste.