Wrap garlic with 1 tbsp. EVOO in foil and grill until tender, about 20 minutes; squeeze cloves from skins. Brush squash, zucchini and onion with remaining 3 tbsp. EVOO; season with salt and pepper. Grill until charred, 10 minutes. Using a food processor, puree veggies with parmesan, walnuts, thyme and garlic. Serve with chips.