Lightly salt the sliced zucchini and squash and let them sit for about 10 minutes. Pat them dry with paper towels to remove excess moisture. Roast at 425°F (220°C) to ensure the vegetables caramelize and crisp up. Spread the squash out in a single layer on a large baking sheet. Overcrowding will cause them to steam rather than roast. Make sure the oven is fully preheated before adding the vegetables.