PREHEAT oven to 325° F. Grease 8 1/2 or 9-inch heart-shaped pan.
COMBINE flour, baking soda and salt in small bowl. Beat butter, brown sugar, granulated sugar and vanilla extract in large mixer bowl until creamy. Beat in egg. Gradually beat in flour mixture. Stir in 1 1/3 cups Valentine morsels; spread into prepared pan.
BAKE for 35 to 40 minutes or until golden brown. Let cool in pan for 10 minutes; remove to wire rack or serving platter. Sprinkle 1/2 cup semi-sweet morsels in center of heart. Let stand for 5 minutes or until morsels are shiny; spread evenly leaving a border. Sprinkle remaining 1/3 cup Valentine Morsels onto chocolate. Cool completely before serving.