HEAT oven to 350°F.
PREPARE cake batter as directed on package. Mix cream cheese, egg and sugar until blended.
RESERVE 3/4 cup pie filling for garnish. Spoon 2 Tbsp. cake batter into each of 24 paper-lined muffin cups. Top each with 1 Tbsp. each of the cream cheese mixture and remaining pie filling. Cover with remaining cake batter.
BAKE 20 to 25 min. or until toothpick inserted in centers comes out clean. Cool in pans 5 min. Remove from pans to wire racks; cool completely.
TOP cupcakes with COOL WHIP and remaining pie filling just before serving.