PREHEAT oven to 350° F. Grease 9-inch heart-shaped pan.
PLACE whole bar of dough in prepared pan. Allow to soften for 5 to 10 minutes. Using fingertips, pat dough gently to cover bottom.
BAKE for 17 to 19 minutes or until golden brown. Cool in pan on wire rack for 10 minutes; remove to wire rack to cool completely.
MICROWAVE morsels in small, microwave-safe bowl on HIGH (100%) power for 45 seconds; stir. Microwave at additional 10-second intervals, stirring until smooth. Spread over cookie to within 1-inch of edge.