MICROWAVE potatoes as directed on package. (Do not mash.)
MEANWHILE, cook onions in large skillet sprayed with cooking spray on medium heat 2 min., s tirring frequently. Add pasta sauce, thyme and garlic powder; mix well. Simmer 3 to 4 min. or until heated through, stirring frequently.
PLACE potatoes in large bowl. Add milk; mash until ingredients are well blended and potatoes are mashed to desired consistency. Add cheese, bacon and pasta sauce mixture; mix well. Sprinkle with chives.