Heat oven to 425˚F. Spray a 9x13-inch baking dish with cooking spray. Mix ⅓ cup hot pepper sauce, oil, and garlic in large bowl. Stir in potatoes until well coated. Spread in even layer in prepared baking dish. Bake 20 to 25 minutes, stirring occasionally, until crisp and tender.
Toss chicken in bowl with remaining 2 tablespoons hot sauce. When potatoes are tender, sprinkle with ½ cup cheese; top with chicken, bacon, and remaining 2 cups cheese. Return baking dish to oven; bake 10 to 15 minutes or until cheese is melted and bubbly. Remove from oven; sprinkle with green onions. Serve with ranch dressing.