Line a 13”X9”X2” baking pan with wax or parchment paper, extending the paper over the edges of the pan. Set aside.In a large saucepan, melt butter over medium heat. Stir in sugar and milk. Bring mixture to a boil, stirring constantly. Boil gently for 5 minutes stirring constantly.Remove saucepan from heat and slowly stir in chocolate chips. Stir until chocolate melts. Then stir in prunes, marshmallow creme, walnuts and vanilla until well combined. Spread mixture in the prepared pan. Chill in refrigerator until firm, overnight or at least 3 hours.
To serve, use the wax/parchment paper to lift fudge from pan. Cut into pieces. Keep extra pieces refrigerated.