Preheat oven to 400°F. In a roasting pan combine zucchini, summer squash, onion, fennel, sweet peppers, and eggplant. Drizzle with the 3 tablespoons oil; toss to coat. Roast for 45 to 50 minutes or until vegetables are tender, stirring twice. Transfer to a very large bowl; cool.
Meanwhile, cook pasta according to package directions. Drain, rinse, and cool slightly. In a large bowl combine pasta and the roasted vegetables.
For pesto, in a blender combine garlic, the 1 cup torn basil, the cheese, and walnuts; cover and pulse with several on/off turns until chopped. With blender running, gradually add the 1/2 cup oil, the lemon juice, and the 1/2 teaspoon salt.
Add the pesto to pasta-vegetable mixture, stirring gently to coat. Stir in cherry tomatoes. Season to taste with additional salt and black pepper. Serve at room temperature. If desired, sprinkle with additional basil.
Walnuts are an inexpensive (and heart-healthy) alternative to using pine nuts in pesto.