Cook the spaghetti according to package directions. Drain and rinse with cold water to stop the cooking. Let cool.
In a large bowl, toss the cooled spaghetti with the Italian dressing and Salad Supreme seasoning.
Add the tomatoes, cucumber, bell pepper, red onion, and olives. Toss to combine.
Sprinkle with Parmesan cheese and toss again.
Cover and refrigerate for at least 2 hours before serving. Toss before serving and add more dressing if needed.
Notes
The pasta absorbs the dressing as it sits, so reserve extra Italian dressing to add before serving. This salad is best made the day before so the flavors have time to develop.