Beat together butter and shortening for 2 minutes. Slowly beat in confectioners' sugar. Add vanilla and salt; beat for 1 minute. Mound 1/4 cup frosting in center of top of each larger cupcake.
For faces, add M&M's, pieces of licorice and halved jellybeans (see photo).
For hats, dab frosting on mini cupcakes, invert and stick to chocolate wafers. Put one on each icing mound.