I've been making this for years. It is excellent.
1 cup butter
4 cups sugar
2 (5-oz) cans evaporated milk (1 1/3 cups total)
1 (12-oz) pkg semi sweet chocolate chips
1 (7-oz) bar Symphony Milk Chocolate, broken in pieces
1 (7-oz) jar marshmallow creme
1 tsp vanilla
Line a 9 x 13" pan with foil, extending the foil over the edges of the pan. Butter the foil and set aside. Butter the sides of a heavy-duty saucepan. In the saucepan, combine the butter, sugar and evaporated milk. Cook and stir over medium-high heat until mixture boils. Reduced heat to medium and continue cooking, stirring constantly, for 10 minutes. Remove from heat and add the chocolate chips, chocolate bar, marshmallow creme and vanilla. Stir until well combined and melted. Beat by hand for one minute. Spread in the prepared pan. Score into 1" squares while still warm. Cool. When fudge is completely cooled, remove fudge from pan and cut completely into squares. Store in a tightly-covered container, in the refrigerator.