Preheat oven to 400ºF.
Place a large pot of water over high heat and bring up to a boil to cook the pasta. Once at a boil, add some salt and the pasta and cook until al dente, according to package directions. Right before draining, remove and reserve 1 cup of the pasta cooking water. Drain pasta thoroughly, return to the pot and reserve.
While the pasta is cooking, place chopped zucchini, yellow squash, red pepper and onion on baking sheet. Drizzle the vegetables with 3 tablespoons EVOO, and season with salt and freshly ground black pepper. Roast for about 15 minutes or until tender and golden brown.