PREHEAT oven to 400°F. Drizzle lemon juice over prepared apples. Remove pastry shells from foil plates. Slightly roll out pastry. Cut round corners to create square shape. Repeat with second pastry.
PLACE apple in centre of each square. Spoon sugar into apple centres; sprinkle with cinnamon. Moisten 4 corners with water. Lift up and join corners together to enclose each apple. Pinch edges to seal. Brush pastry with egg. Place in lightly greased baking pan.
BAKE 30 min. or until pastry is crisp and lightly brown. Lay cheese strips across apple tops. Spoon 1 Tbsp. whipped topping on each dumpling. Cut dumpling in half. Serve with maple syrup, if desired.