PREHEAT oven to 350º F. Line 8-inch-square baking pan with foil; lightly grease.
PLACE whole bar in prepared pan. Allow to soften for 5 to 10 minutes. Using fingertips, pat dough gently to fill pan.
BAKE for 24 to 26 minutes or until wooden pick inserted in center comes out slightly sticky. Cool completely in pan on wire rack.
LIFT from pan; remove foil. Cut into 12 pieces. Arrange pieces close together on serving platter. Top with pie filling, whipped topping and grated chocolate.