HEAT oven to 375ºF.
ADD potatoes to large saucepan of boiling water; cook 20 to 25 min. or until tender.
MEANWHILE, cook meat and onions in large nonstick skillet on medium heat 5 to 7 min. or until meat is browned and onions are tender, stirring occasionally. Add flour; cook and stir 1 min. Add frozen vegetables and broth; mix well. Stir in 1/4 cup Cooking Creme; cook and stir 2 to 3 min. or until slightly thickened. Pour into 8-inch square baking dish sprayed with cooking spray.
DRAIN potatoes, reserving 1/4 cup cooking water. Return potatoes and reserved water to pan; mash until smooth. Stir in remaining Cooking Creme; spread over meat mixture.
BAKE 25 to 30 min. or until heated through.