PLACE 1 fish fillet on each square of foil, about 2 in. from one of the sides. Drizzle with 1 tsp. of the dressing. Sprinkle with about 1/4 tsp. thyme and top with 1/2 cup of the vegetables.
FOLD the opposite sides of the foil over the fillets. Fold up the open ends of each foil packet to seal. Place on a baking sheet.
BAKE at 350°F for 25 min. Remove from oven and let stand 5 min. Place one packet on each serving plate; slit top with a knife. Spoon 1 Tbsp. CHEEZ WHIZ over each fish fillet.