In a large saucepan, bring 4 quarts of water to a boil. Add the rotini, reduce to a low boil and cook to the desired doneness, about 10 minutes, adding the tortellini during the last 6 minutes of cooking. Drain and transfer to a large bowl.
Toss the tomatoes with the salt and pepper in a small bowl.
While the pasta is still warm, add the tomatoes, Cheddar and oil and toss to combine. Serve warm.
Adapted from "Georgia Cooking in an Oklahoma Kitchen" by Trisha Yearwood © Clarkson Potter 2008. Provided courtesy of Trisha Yearwood. All rights reserved.