Boil the Pasta: Bring a large pot of heavily salted water to a rolling boil. Cook the spaghetti according to the package instructions, adding 1-2 extra minutes so the pasta remains tender when chilled.

Rinse and Cool: Drain the cooked pasta in a colander and immediately rinse it under cold running water to stop the cooking process and remove excess starch. Set aside.

Prep the Vegetables: While the pasta boils, prepare your vegetables. Add the diced zucchini, halved cherry tomatoes, green and red bell peppers, red onion, cucumber, and drained black olives to a very large mixing bowl.

Whisk the Dressing: In a separate, smaller bowl, combine the bottle of Italian dressing, grated Parmesan cheese, sesame seeds, paprika, celery seeds, and garlic powder. Whisk vigorously until the spices are fully incorporated.

Toss Together: Add the cooled spaghetti to the large bowl with the chopped vegetables. Pour the seasoned dressing mixture over the top. Use kitchen tongs to toss everything together until the pasta and vegetables are evenly coated.

Chill and Serve: Cover the bowl tightly with plastic wrap or a lid. Place in the refrigerator to marinate for at least 3 hours before serving. Give it a quick toss right before serving to redistribute the dressing. Enjoy!