BEAT butter and sugar with electric mixer on medium speed until light and fluffy. Blend in egg and vanilla. Mix flour, baking powder and salt. Add to butter mixture; mix well. Refrigerate 1 hour.
ROLL out dough to 1/8-inch thickness on lightly floured surface. Cut with heart-shaped cookie cutter. Place on parchment paper-lined cookie sheet. Refrigerate 30 minutes.
BAKE at 350°F for 10 minutes or until edges are lightly browned. Cool. Dip 1 side of each cookie in chocolate. Place on wire rack to dry.
Special Extra: Sprinkle chocolate side of cookie with red, white and pink colored sprinkles.