Spread cream cheese into bottom of 13 x 9-inch baking dish. Stir together chicken, cranberry sauce, chili sauce, Worcestershire sauce, vinegar, mustard and red pepper flakes in medium bowl. Spoon mixture over cream cheese in baking dish. Sprinkle with cheese. Bake for 20 to 30 minutes or until heated through. Sprinkle with onions. Serve with crackers for dipping.