Melt remaining semi-sweet chocolate. Use toothpicks to dip remaining cookie balls, 1 at a time, in melted chocolate, dipping 1 side of each ball in chocolate, then turning to dip other side, leaving "V"-shaped white centre; let excess chocolate drip back into bowl. Return to parchment-covered rimmed baking sheet. Pipe remaining semi-sweet chocolate onto balls for the buttons and bow ties, placing the ties over the toothpick holes to cover. (Or, pipe buttons onto balls, then pipe bow ties onto parchment paper; refrigerate until firm. Attach bow ties over toothpick holes on balls with small dabs of melted chocolate.) Refrigerate until firm.