Line a 13 x 9 inch baking pan with wax paper, extending the paper over the edges of the pan.
Set the pan aside.
In a large saucepan, melt the butter.
Stir in the sugar and the milk.
Bring the mixture to a boil over medium heat, stirring constantly.
Boil for 5 minutes, stirring constantly.
Remove the saucepan from the heat and slowly stir in the chocolate chips.
Stir until the chocolate melts.
Then stir in the prunes, marshmallow cream, walnuts, and vanilla until well combined.
Spread the mixture in the prepared pan.
Chill in the refrigerator until firm.
To serve, use the wax paper to lift the fudge from the pan.
Then cut the fudge into pieces.