Line a 13x9 inch baking dish with foil and butter the foil.
Step 2
In the top half of a double boiler combine the butter or margarine, evaporated milk and sugar. Cook on medium heat for 12 minutes or until it reaches a temperature of 236 degrees F (112 degrees C). Remove from heat and stir in the chocolate chips, vanilla and marshmallow creme. Stir until chocolate chips melt then mix in the chopped walnuts. Spread mixture into the prepared pan. Score into squares while still warm. Refrigerate until firm then cut along the scored lines.