Bring a pot of water to a boil and cook 12 ounces Pasta rotini or macaroni according to package directions until al dente. Drain well, then rinse under cold water to stop the cooking process.
In a large mixing bowl, whisk together 3/4 cup Mayonnaise, 1/2 cup Sour cream , 1 tablespoon Sugar , 1 tablespoon Apple cider vinegar , 1/2 teaspoon Salt, and 1/2 teaspoon Black Pepper until creamy and well combined.
Add the diced 1 cup Bell peppers, 1/2 cup Celery, 1/4 cup Red onion (if using), and 1 cup Cheddar cheese , stirring until everything is coated in the dressing.
Gently fold the cooled pasta into the mixture, making sure every piece is covered in the creamy dressing.
Cover the bowl and refrigerate for at least 2 hours, or overnight, so the flavors can develop.
Give the salad a good stir before serving. Garnish with extra cheese or fresh herbs for a delicious finishing touch.