Heat oven to 450°F. Line 15x10x1-inch pan with foil; spray foil with cooking spray.
Cut potatoes into thin wedges. In large bowl, mix potatoes, oil, chili powder and garlic powder; toss to coat. Place in pan.
Bake 25 to 30 minutes or until tender and golden brown, turning once.
Meanwhile, in medium bowl, mix all dip ingredients except onions. Sprinkle onions on top of dip.