Place a 16-inch long piece of plastic wrap over the top of a 12-cup mini-muffin pan.  Repeat with a second pan.  Set pans aside.  Chop both kinds of chocolate and place in a heavy 2-qt. saucepan.  Over low heat, heat the chocolate, stirring frequently, until melted and smooth.  Remove the saucepan from the heat.  Place the pretzels in a heavyweight plastic bag.  Crush the pretzels lightly with a rolling pin; stir into the melted chocolate.  Spoon the chocolate mixture into the mini-muffin pans to fill almost halfway, or place the chocolate mixture in a heavyweight plastic bag.  With scissors, snip off one corner of the bag and squeeze the chocolate mixture into the mini-muffin cups.  Gently tap the muffin pans on the counter to make the chocolate mixture even.  Refrigerate for 30 minutes or until the chocolate is firm and fully set.  Remove the pans from the refrigerator.  Peel away the plastic wrap from the chocolates and trim any rough edges with a knife.  Wrap each chocolate in a gold or silver foil square.  (Gold and silver foil squares are available wherever chocolate and candy making supplies are sold.)  Makes 24.