Combine butter, evaporated milk, sugar, and salt in saucepan over medium
heat, stirring occasionally. Bring to full boil. Cook 4-5 minutes, stirring constantly.
Remove from heat. Stir in marshmallows, peanut butter chips, peanut butter, and
vanilla. Stir vigorously for 1 minute, until marshmallows melt and blend. Pour into
8 inch square buttered pan. Cool.
Melt chocolate chips; spread on fudge. Chill before serving.