1Heat oven to 400º. Spread zucchini, yellow squash, bell pepper, onion and garlic in jelly roll pan, 15 1/2x10 1/2x1 inch. Spray vegetables with cooking spray. Sprinkle with salt and red pepper.
2Bake about 30 minutes, turning vegetables once, until vegetables are tender and lightly browned.
3Place vegetables in blender or food processor. Cover and blend on high speed about 1 minute, stopping blender occasionally to scrape sides, until smooth.
4Serve warm, or refrigerate at least 2 hours until chilled. Serve with dippers.