Microwave chocolate in large microwavable dish on high 2-3 minutes stirring in between. stop every 30-40 seconds and sir
stir until chocolate is melted
stir in vanilla and walnuts.spread in foil lined 8 inch square pan.refrigerate 2-3 hours until firm
if you are making the double layered fudge mix the white chocolate with the 1/2 cup condensed milk and heat until melted stirring until melted. top the chocolate fudge with the white mixture before refrigerating.