Cook spaghetti in salted water until al dente. Drain and rinse under cold water to stop cooking.
Toss cooled pasta with olive oil in a large bowl to prevent sticking.
Add cherry tomatoes, bell peppers, red onion, black olives, Parmesan, and parsley.
Pour in Italian dressing and mix until evenly coated.
Season with salt and pepper to taste.
Chill in the refrigerator for at least one hour before serving to let the flavors fully develop.
